Iowa State University Physics & Astronomy Video and Laser Disk Collection
ENCYCLOPEDIA OF PHYSICS DEMONSTRATIONS
This is a set of 25 videodisks containing about 600 professionally-produced demonstrations, often live ones carried out by students, and often including extra graphics to help viewers understand the physics.
The demonstrations are numbered in the form Demo 16-14, which refers to demonstration 14 on disk 16. The demonstrations are classified into "Chapters" focusing on particular topics. Demo 16-14, which shows the levitation of a tiny rare earth magnet over one of the new high-temperature superconductors, is the first demonstration of Chapter 37, "Crystals and Low Temperature."
Retrun to Lecture Demonstration Home Page
Index
Chapter 6- Action and Reaction
Chapter 8- Work, Energy and Power
Chapter 12- Rotational Kinematics
Chapter 13- Rotational Acceleration and Energy
Chapter 14- Conservation of Angular Momentum
Chapter 16 - Rotational Phenomena
Chapter 24- Properties of Sound
Chapter 25- Standing Sound Waves
Chapter 34- Laws of Thermodynamics
Chapter 37 - Crystals and Low Temperatures
Chapter 40- Electrostatic Induction
Chapter 42- Resistance and DC Circuits
Chapter 43- Voltage Drops and I 2 R Losses
Chapter 44- Non-Ohmic Resistance
Chapter 45- Electrochemical Effects
Chapter 46- Capacitance and RC Circuits
Chapter 47- Magnetism and Magnetic Fields
Chapter 48- Magnetic Fields From Currents
Chapter 49- Magnetic Properties of Matter
Chapter 50- Magnetic Forces on Currents
Chapter 51 - Electromagnetic Induction
Chapter 54- Inductance and LR circuits
Chapter 56 - Electromagnetic Waves
Chapter 59- Refraction and Internal Reflection
Chapter 66- Optical Activity (continued)
LD-1: DISK 1
Demo 01-01 (frame 535) Aims to clarify notion of standard units by comparing meter stick with yardstick (which has been marked off in 1 inch units). A 1 kilogram mass is compared with a 1 pound weight of the same material and clock with a second hand is shown (64 s). Equipment: A 1 kg and 1 lb mass, a meterstick and yardstick, and a clock with second hand.
Demo 01-02 (frame 2463) Demonstrates the parallelogram method of vector addition (104 s). Equipment: None (demo is computer animation).
Demo 01-03 (frame 5588) Graphic demonstration of "head-to-tail" method of vector addition (67 s). Equipment: None (demo is computer animated).
Demo 01-04 (frame 7594) Graphic demonstration of separating a vector into its corresponding components (56 s). Equipment: None (demo is computer animated).
Demo 01-05 (frame 9290) Various examples of the dot product of two vectors (53 s). Equipment: None (demo is an animation).
Demo 01-06 (frame 10883) Explains the definition of the cross product while showing the concept of right hand rule (62 s). Equipment: None, computer animated.
Demo 01-07 (frame 12742) Examining vectors in 3-D (85 s). Equipment: A model vector coordinate system with a resultant vector that is free to move in space.
Demo 01-08 (frame 15301) This demonstration illustrates constant velocity using an air track glider. Air track is fitted with spring bouncers for an elastic collision with the end of the air track, reversing direction of air cart but keeping same speed (63 s). Equipment: Air track, blower system and heavy glider.
Demo 01-09 (frame 17185) The addition and subtraction of vectors using toy bulldozers and a paper sheet (53 s). Equipment: 2 toy bulldozers, long sheet of paper or plastic with evenly spaced grid markings and rollers for sheet if desired.
Demo 01-10 (frame 18768) A ball rolls down an incline, illustrating motion with constant acceleration. Plots of x(t), v(t) and a(t) as well. Equipment: An inclined track with steel ball and lights positioned at 1,4,9,16 and 25 units to show various relationships. A timing mechanism to permit the ball to descend at same moment that lights flash.
Demo 01-11 (frame 21600) A tilted air track allows a glider to travel with constant acceleration. Demo is done for three different angles of tilt (87 s). Equipment: Air track, blower system, heavy glider and multiple spacing shim to incline track.
Demo 01-12 (frame 24223) The geometrical nature of the distance versus time curve for constant acceleration is shown by dropping two strings. One string has weight attached at equal intervals and the other with weights spaced geometrically. The analysis of the sound emitted when the strings hit a board will verify that distance versus time for falling bodies is a parabola (33 s). Equipment: 2 strings with weights placed as mentioned previously and a board for judging time intervals when the weights strike it.
Demo 01-13 (frame 25230) Drop a meter stick to analyze the reaction time of a person (51 s). Equipment: A meter stick and 2 demonstrators.
Demo 01-14 (frame 26767) Shows that acceleration in free fall is independent of mass, in the absence of other forces. A metal disk and piece of paper are dropped in an evacuated tube (63 s). Equipment: A penny and feather tube and a vacuum pump.
Demo 01-15 (frame 28670) The horizontal Atwood's machine involves acceleration of an air track glider by a small mass attached to the glider by a string passing over a pulley (71 s). Equipment: Level air track, blower, glider, 2 low-friction pulleys, lightweight string, paper clips, stopwatch and appropriate masses.
Demo 01-16 (frame 30819) A classical Atwood's machine is used to study force and acceleration (71 s). Equipment: Low-friction pulley, lightweight string. 2 equal masses, 2 small rider weights to take system out of static balance, stopwatch, two-meter stick and a catch system so that riders are not lifted off without disturbing their linear motion.
Demo 01-17 (frame 32964) A flexible string is attached to front of an air glider and used to pull the air cart along the track with constant force (38 s). Equipment: Air track, blower, heavy glider, 2 low friction pulleys and a lightweight spring with a slow spring constant.
Demo 01-18 (frame 34108) A slinky is held at one end and then dropped to analyze motion of the spring under constant acceleration (24 s). Equipment: A slinky.
Demo 01-19 (frame 34829) A candle is placed in a sealed jar and dropped from some height. The candle goes out once dropped because the constant acceleration of free fall eliminates convection currents, thus preventing any oxygen from reaching the flame (58 s). Equipment: A quart jar with candle fixed to underside of lid, source of flame and catching device for jar.
LD-2: DISK 2
Demo 02-01 (frame 538) Illustrates the independence of velocity components by showing that accelerated motion along a vertical line is independent of horizontal motion. This is accomplished by dropping a ball in free fall at the same time a ball is released with a horizontal velocity (60 s). Equipment: Spring-loaded gun designed to shoot a ball horizontally while simultaneously dropping a ball and 2 balls.
Demo 02-02 (frame 2340) The traditional "Hunter and the Monkey" gun experiment to demonstrate that gravity acts on a body independently of its initial state of motion (55 s). Equipment: A projectile, target, gun and a support that releases target at instant the gun is fired.
Demo 02-03 (frame 4013) A cannon car moves with constant horizontal velocity and fires a ball vertically at some instant. The ball moves in parabolic arc and returns to the car (51 s). Equipment: Cannon car (cocking mechanism, trigger release and funnel), trigger tip on the track and projectile.
Demo 02-04 (frame 5559) A ball is fired vertically from a cannon car accelerating on an incline and a ball is fired from a car which accelerates after the ball is fired. Motion of ball is described in both cases (60 s). Equipment: Inclined track, cannon car, projectile and pulley with string and weight.
Demo 02-05 (frame 7372) Pucks are projected at an uphill angle along a tilted air table. Demonstration of constant velocity perpendicular to the tilt and constant acceleration in direction of the tilt. Equipment: Air table and pucks.
Demo 02-06 (frame 9450) Projectiles are released at different angles but with the same muzzle velocity to determine what angle gives a maximum range (63 s). Equipment: Spring gun and markers for points of impact.
Demo 02-07 (frame 11347) A ping-pong ball is used to show vector velocity addition (47 s). Equipment: Ping-pong ball and string.
Demo 02-08 (frame 12780) A toy bulldozer moves on a plastic sheet to illustrate a variety of vector velocity examples (85 s). Equipment: Toy bulldozer and long sheet of paper or plastic.
Demo 02-09 (frame 15338) Balls are allowed to slide along the sides of a wire triangle oriented in a vertical plane (the triangle sides are chosen so that a ball released from any upper point will take the same amount of time to reach any lower point). (43 s). Equipment: A substrate and 3 brass ball bearings drilled slightly oversized through their centers to permit stringing with the wire.
Demo 02-10 (frame 16652) Shows experimentally how a boat can sail with a component of velocity against the wind (46 s). Equipment: A fan and toy sailboat.
Demo 02-11 (frame 18040) This demonstration uses a standard liquid accelerometer, mounted on an air track glider, to show that there is no net force component down an incline along which an object is freely accelerating, in the frame of reference of the moving object (36 s). Equipment: Tilted long air track, blower system and large glider with liquid accelerometer.
Demo 02-12 (frame 19139) A demonstration of Newton's first law, by showing that if an object experiences no force, it will not move. This is accomplished with air gliders (40 s). Equipment: Air track, blower system, heavy cart and large glider with extra masses.
Demo 02-13 (frame 20356) The hanging cylinder. A heavy cylinder hangs by a thin rope from a rigid frame. A second identical thin rope is attached to the bottom of the cylinder, and a short metal rod is attached to the bottom end of the lower rope. The experiment shows that a gradual downward force applied to the rod breaks the top rope, and a sharp force breaks the lower rope (32 s). Equipment: Massive object, string loops, metal rod and frame assembly shown in demo.
Demo 02-14 (frame 21340) Demonstration of inertia with rocks and mallet (27 s). Equipment: Large rock, fake rock of similar size and appearance (demo uses foam) and large rubber hammer.
Demo 02-15 (frame 22146) Pulling a cloth out from under a dining room setting to show inertia (35 s). Equipment: Tabletop, tableware and tablecloth (preferably silk).
Demo 02-16 (frame 23195) Three eggs are positioned on stands which are on a pizza pan resting on beakers of water. The pan is shot out from under the eggs fast enough that they fall in the water (40 s). Equipment: Containers of water, pizza pan, cylinders, appropriate number of raw eggs and stiff broom.
Demo 02-17 (frame 24414) This demonstration uses the inertia of a rapidly moving pencil to impale it on a piece of 1/2 inch plywood (47 s). Equipment: Barrel for firing pencil, plywood and fire extinguisher.
Chapter 6- Action and Reaction
Demo 02-18 (frame 25847) Two identical air track gliders are used to illustrate Newton's third law of motion (52 s). Equipment: Air track, blower system, 2 gliders, air shield, source of flame and supply of string.
Demo 02-19 (frame 27418) Two air track gliders of unequal mass are used to highlight Newton's third law (46 s). Equipment: Air track, blower system, 2 gliders, air shield, source of flame and supply of string.
Demo 02-20 (frame 28801) The action and reaction forces of a radio-controlled car on a board below it that is on rollers (36 s).
Demo 02-21 (frame 29903) A car with a fan mounted on it is used to show Newton's third law. A sail is placed in front of the fan and the car will not move (49 s). Equipment: Small cart with motor driven fan, sail and sizable external fan.
Demo 02-22 (frame 31388) A small canister of compressed carbon dioxide is used to accelerate a type of Hero's engine, illustrating the idea of action and reaction (35 s). Equipment: Carbon dioxide cartridges, firing mechanism and rotating bar.
Demo 02-23 (frame 32456) Air is pumped into the body of the rocket under pressure. When the air is released, the pressure within the rocket forces the air out as exhaust. When water is exhausted with the pressurized air, the rocket experiences much greater thrust. This is used to demonstrate the idea of action and reaction as applied to rocketry (97 s). Equipment: Toy water rocket and a supply of water
Demo 02-24 (frame 35378) A carbon dioxide fire extinguisher serves as the engine for a wagon rocket, illustrating Newton's third law (51 s). Equipment: Wagon, device to safely cradle fire extinguisher and fire extinguisher itself.
Demo 02-25 (frame 36907) A toy propeller is used to demonstrate Newton's third law (32 s). Equipment: Toy propeller.
Demo 02-26 (frame 37868) A center of mass balance board is used with 2 carts to illustrate action and reaction forces (56 s). Equipment: Pivot base for see-saw, plywood, 2 carts, string loops, a torpedo level and source of flame.
LD-3: DISK 3
Demo 03-01 (frame 525) Demonstration is an introduction to the air track, showing that gliders can move virtually without friction (33 s). Equipment: Air track, blower system and gliders.
Demo 03-02 (frame 1528) A spring scale is attached to a block of wood to show that the coefficient of static friction is greater than that of sliding friction for the same two surfaces (43 s). Equipment: Block of wood, string and a spring scale.
Demo 03-03 (frame 2826) This demonstration shows that the frictional force is independent of the area of contact between two surfaces by pulling a wooden board on one of its sides and then pulling it on a shorter side (52 s). Equipment: Length of wood, chain and spring scale.
Demo 03-04 (frame 4385) A board is pulled along a horizontal surface by a rope attached to a spring scale, measuring the kinetic frictional force. Weights are then added to illustrate how the friction force changes as the normal force varies. A direct proportionality results (67 s). Equipment: Length of wood, string, spring scale and weights.
Demo 03-05 (frame 6418) The demo illustrates that the frictional force between different surfaces is very different. This is done by placing a brass block on each of the surfaces and altering the angle of incline until they slide (63 s). Equipment: A piece of 1/2 inch plywood covered with 4 different materials (rubber, wood, sandpaper and Teflon) and four equal weights.
Demo 03-06 (frame 8313) Rolling and sliding. A toy car with either its front or rear wheels locked slides down an incline. The pair of wheels that are locked will slide, while the others roll. The pair that are rolling have greater friction, and will lag behind (27 s). Equipment: Toy car, tilted surface and a locking bar to disable the wheels.
Chapter 8- Work, Energy and Power
Demo 03-07 (frame 9121) A pile driver pushes nails into a block of wood, demonstrating that the greater the original potential energy, and thus its kinetic energy at impact, the further the nail is driven into the wood (54 s). Equipment: A pile driver and a block of wood with several nails pre-driven to equal initial depth.
Demo 03-08 (frame 10763) A toy gun fires two balls of different weight to demonstrate that the height the ball travels depends on the initial weight, besides the energy imparted from the gun (37 s). Equipment: Toy gun and 2 balls of differing weight.
Demo 03-09 (frame 11870) Potential energy into kinetic energy. This demonstration makes use of the potential energy stored in a spring to launch a small toy (29 s). Equipment: Spring toy with suction base.
Demo 03-10 (frame 12742) An air track glider is attached to an arm that compresses a spring. When released it moves up the inclined air track. This illustrates that the energy stored in a spring is proportional to the square of the distance the spring is compressed (75 s). Equipment: Tilted air track, blower system, calibrated spring launch mechanism, glider and appropriate scales for launch mechanism and air track distances.
Demo 03-11 (frame 15005) The "Hopper Popper": half of a handball is flipped inside out and dropped onto the floor. The mechanical potential energy stored in the ball when it was distorted is released when the ball hits the floor. This additional energy allows the ball to bounce higher than the height at which it was dropped (34 s). Equipment: Half of a handball that can be turned inside out.
Demo 03-12 (frame 16027) A ball is allowed to roll back and forth in a V-shaped track to illustrate the transformation between mechanical potential energy and kinetic energy (32 s). Equipment: An energy well and a ball.
Demo 03-13 (frame 17005) Simple pendulum with pivot bar. A simple pendulum is raised and released from rest such that when it reaches its lowest point the string is intercepted by a post, effectively creating a pendulum with a shorter length. The height to which the bob rises after being intercepted by the post is the same as the release height (39 s). Equipment: Tall ring stand, simple pendulum with massive bob and pivot bar.
Demo 03-14 (frame 18178) A bowling ball pendulum is released from rest in front of the demonstrators nose. It swings back but does not hit the demonstrator (40 s). Equipment: Simple pendulum with bowling ball bob, secure support system and a courageous demonstrator.
Demo 03-15 (frame 19380) Balls are released from the same height at the top of three tracks. The height it rises to is the same, and does not depend on the angle of the track (70 s). Equipment: Lengths of U-channel with identical lengths and angles on one end and differing angles and lengths on the other, support system, a ball that will roll and not slide and a position marker.
Demo 03-16 (frame 21479) An electrical generator that is cranked by hand will stop in about 5 seconds if there is no load. However, if a light bulb is connected to the output of the generator, the load on the generator consumes energy, and the system stops in 1 second (42 s). Equipment: Electrical generator, light bulb and socket, pair of long leads, short lead and a switch.
Demo 03-17 (frame 22759) The conversion of mechanical energy to electrical energy via a weight attached to a string wrapped around a pulley on the shaft of an electrical generator. When a light bulb is attached to the output of the generator the weight falls much more slowly (39 s). Equipment: Electrical generator, string, heavy weight with eye screw and a light bulb.
Demo 03-18 (frame 23938) A prony brake applies a constant frictional force, which is used to determine the relationships between force, work and power (61 s). Equipment: Prony brake, spring scale, leather strap and heavy weight.
Demo 03-19 (frame 25773) This demonstration illustrates the concepts of stable, neutral and unstable equilibrium, using a cube, sphere and cone, respectively (70 s). Equipment: A cube, sphere and cone.
Demo 03-20 (frame 27875) The center of mass of an irregularly-shaped object. When a plane irregular object is suspended from any point on the object, it will hang such that the center of mass is directly below the point from which it is suspended, and the demonstration finds the center of mass by hanging the object from 2 points and intersecting the straight lines made from a plumb bob (80 s). Equipment: Tall ring stand, support rod, irregular shaped body, plumb bob and chalk.
Demo 03-21 (frame 30274) Center of mass of disc thrown in air. A disc is thrown through the air, first with its center of mass at the center of the disc, then with its center of mass displaced from the center of the disc, and the paths of the center of mass are traced out in each case (40 s). Equipment: Cardboard or Styrofoam disc, disc weight to move from center to edge position and a mark to aid in visibility of center of mass.
Demo 03-22 (frame 31479) An upright chair is balanced on a vertical rod supporting the chair at a point under the seat at the center of the legs. This is achieved by placing heavy weights in holes strategically drilled in the ends of the chair legs (37 s). Equipment: Vertical support rod and wooden chair with added weights.
Demo 03-23 (frame 32613). A toy clown rolls along a tightrope. If it is holding long rods the center of mass is below the rope and it rolls, if not then the clown falls off (34 s). Equipment: Toy clown on unicycle with balance bar and counterweights and string.
Demo 03-24 (frame 33648) A double cone rolls on a pair of rails in such a way as to appear to roll uphill. In reality the center of mass becomes lower as the double cone rolls along the rising rails (50 s). Equipment: Inclined rails whose distance of separation decreases to a near point at opposite lower end, cylinder and double cone.
Demo 03-25 (frame 35162) A disc that rolls uphill. A wooden disc is loaded with a heavy weight near its perimeter, causing the center of mass to be located well off center. By careful positioning of the disc it can roll up and down the incline (30 s). Equipment: Low angle incline plane and heavy wooden disc.
Demo 03-26 (frame 36071) This demonstration illustrates the effect of the center of mass and torques using two toppling cylinders. By placing balls of different weight one on top of the other the tube can be made to lean or fall over when lid is removed (45 s). Equipment: Aluminum cylinder fitted with a cap and hollow lower half, aluminum cylinder fitted with a cap and its 2 ends cut at an angle, ping-pong ball and steel sphere.
Demo 03-27 (frame 37419) A long flat piece of wood, weighted at one end, is slid across an air table while it is rotating. The center of mass moves in a straight line (49 s). Equipment: Air table, blower system, flat glider and mark for center of mass to aid visibility.
LD-4: DISK 4
Demo 04-01 (frame 474) A force board allows the investigation of the conditions for equilibrium of three or more forces. Components of the forces are graphed, showing why the system is in equilibrium (59 s). Equipment: Vertically supported board to support 3 or more pulleys, center ring with lengths of string tied to it and 3 weights.
Demo 04-02 (frame 2250) A weight is hung from a clothesline to show that it sags, and then discussion of the amount of force needed to straighten the line with the weight on it (59 s). Equipment: Length of light rope, spring scale and weight.
Demo 04-03 (frame 4025) A small cart is held in place on an inclined plane by means of a mass hanging over a pulley. If another force is applied to the cart at an angle with respect to the incline, the cart will move until the force is exactly perpendicular to the incline (71 s). Equipment: 30 degree inclined plane, a rolling body, 2 pulleys, 2 clamps, 2 ring stands and 2 weights to counterbalance the components of the body's weight.
Demo 04-04 (frame 6148) Demonstration that the force can be varied to when doing work on an object, but the distance must also change if the work is to remain the same (55 s). Equipment: Ring stand, pulley, clamp, hook, mass, spring scale and length of string.
Demo 04-05 (frame 7801) A pulley and a spring scale are connected in a metal frame that hangs from an upper spring scale. The free end of the rope is pulled to show how a pulley works (59 s). Equipment: Pulley, 2 spring scales and frame.
Demo 04-06 (frame 9586) The demonstration illustrates some simple machines: inclined plane, lever, screw jack and block and tackle (53 s). Equipment: Inclined plane, spring scale, heavy weight, block with hook, stiff bar, pivot, screw jack, block and tackle and ring stand.
Demo 04-07 (frame 11182) The various types of levers are demonstrated (58 s). Equipment: Ring stand, pivot system, meter stick, spring scale and a weight.
Demo 04-08 (frame 12920) Investigation of the forces developed in 2 types of boom structures. For each case, the tension in the wire is measured for various load weights (58 s). Equipment: Support rod, hook, spring scale, pulley and clamp, length of wire or cable, boom rod with pivot, weight hanger and slotted weights.
Demo 04-09 (frame 14653) An arm model is used to illustrate the forces and torques created by the bicep and tricep muscles. A ball is thrown, showing the action of the muscles in dynamic motion (36 s). Equipment: 2 lengths of tubing positioned so the end of one can pivot about the end of the other and 2 lengths of rope.
Demo 04-10 (frame 15745) A weight is suspended further out on a torque bar, showing that it requires an increasingly greater torque on the handle to lift the weight (54 s). Equipment: Torque bar and weights.
Demo 04-11 (frame 17367) A greater force is required to rotate the board about its hinge when the force is applied closer to the hinge, as shown in the demonstration (76 s). Equipment: Hinge board and spring scale.
Demo 04-12 (frame 19659) A torque wrench is used to illustrate the concept of torque and how torque is applied to the head of a screw (55 s). Equipment: Block of metal, torque wrench and supply of bolts.
Demo 04-13 (frame 21308) Various combinations of weights are applied at various radii on the torque wheel to obtain static equilibrium of torques (64 s). Equipment: Torque wheel and hooked weights.
Demo 04-14 (frame 23230) Balance of a meter stick is maintained by placing various weights at appropriate positions on both sides of the fulcrum (62 s). Equipment: Ring stand with clamps, meter stick with low friction pivot at its center and several weights.
Demo 04-15 (frame 25105) A meter stick is balanced on two fingers, and the fingers are moved together to find the center of mass. Then, one hand is covered in a glove and the other in chalk dust and the experiment is attempted again (133 s). Equipment: Meter stick, rubber glove, chalk dust and a weight with circle of tape.
Demo 04-16 (frame 29106) As a truck moves across the bridge, the equilibrium of torques condition requires that the force required to support the truck is greater at the tower closer to the truck, as shown in the video (69 s). Equipment: 2 platform spring scales, board or model of bridge and loaded toy truck.
Demo 04-17 (frame 31191) A Roberval balance is used to show that equal weights could be placed anywhere on the balance and still be in neutral equilibrium (48 s). Equipment: Roberval balance, 2 equal weights and a small third weight.
Demo 04-18 (frame 32651) The demonstration shows the several forces in operation when a ladder is leaned against a wall (41 s). Equipment: Ladder, clear wall and smooth floor.
Demo 04-19 (frame 33891) An illustration of how a broom can stand on its bristled end if the bristles are spread out (30 s). Equipment: Straw broom.
Demo 04-20 (frame 34809) A demonstrator lies on a bed of nails and has a concrete block smashed on his chest to show that due to the large number of nails a puncture will not result (67 s). Equipment: Bed of nails, pillow, towel or face shield, concrete block and a heavy hammer.
Demo 04-21 (frame 36820) A raw egg is squeezed between 2 hard foam rubber pads. Because the force is distributed over a large area, and because the shape of the egg is an arch, a force of over 150 lbs. can be placed on the egg (75 s). Equipment: Egg crusher, supply of raw eggs, supply of lead bricks and a skillet.
LD-5: DISK 5
Demo 05-01 (frame 477) This demonstration illustrates a variety of collisions between balls. The first group demonstrates collisions between equal masses, followed by collisions between unequal masses. Finally, collisions of a chain of equal balls are shown (86 s). Equipment: 2 billiard balls of equal mass, 2 balls in 3 to 1 mass ratio, 2 balls in 80 to 1 mass ratio and a set of eleven billiard balls to be suspended in air.
Demo 05-02 (frame 3078) Collisions between equal and unequal masses on an air track are studied to show conservation of linear momentum and conservation of energy during elastic collisions (105 s). Equipment: Air track, blower system, 2 equal mass gliders, double and triple mass gliders.
Demo 05-03 (frame 6225) Inelastic and elastic collisions between equal mass gliders are investigated (47 s). Equipment: Air track, blower system and 2 gliders for elastic and inelastic collisions.
Demo 05-04 (frame 7654) The coefficient of restitution of several materials is found by dropping balls of specific materials onto a steel plate (58 s). Equipment: Glass tube, glass ball, steel ball, rubber ball, brass ball and lead ball.
Demo 05-05 (frame 9392) A small ball is placed on top of a larger ball and they are dropped from that initial orientation. The lighter ball flies off very rapidly while the large ball does not bounce (22 s). Equipment: Basketball and softball.
Demo 05-06 (frame 10060) This demonstration shows elastic collisions between a moving air table puck and a stationary puck of equal mass. Collisions vary from a head-on collision to a glancing collision (47 s). Equipment: Air table, glower system and 2 pucks of equal mass.
Demo 05-07 (frame 11474) This demonstration shows elastic collisions between a moving air table puck and a stationary puck of different mass (49 s). Equipment: Air table, blower system and 2 pucks.
Demo 05-08 (frame 12946) This demonstration shows inelastic collisions between a moving and a stationary puck of the same and different masses. Collisions vary from head-on to glancing (32 s). Equipment: Air table, blower system and 2 pucks.
Demo 05-09 (frame 13918) An egg is thrown into a hanging bedsheet, thus stopping slowly enough not to break it, unlike when thrown against a brick wall (30 s). Equipment: Double size bedsheet and supply of raw eggs.
Demo 05-10 (frame 14837) A pile driver is dropped onto a piece of plastic, causing it to break. If a piece of foam rubber is placed on top of the plastic and the pile driver is dropped onto the foam rubber, the foam softens the blow and the plastic does not break. This demonstrates the concept of impulse (50 s). Equipment: Pile driver, supply of stiff plastic and foam rubber block.
Demo 05-11 (frame 16357) A ballistic pendulum is shown and the position of the enter of mass after collision and when the pendulum reaches its highest point is used to determine the speed of the projectile (54 s). Equipment: Ballistic pendulum, projectile and meter stick.
Chapter 12- Rotational Kinematics
Demo 05-12 (frame 17973) This graphics demonstration illustrates the definition of the radian and shows that the circumference of a circle is 6.28 times its radius. Lengths of one radius are bent and placed onto the circumference of a circle, showing the definition of the radian (36 s). Equipment: Circular disc and flexible strip of plastic equal in length to the radius of the disc.
Demo 05-13 (frame 19071) A cylinder of given radius is attached coaxially to a second cylinder of greater radius. The small cylinder is rolled along the edge of a table, showing the cycloidal path (33 s). Equipment: Disc attached to a solid cylinder whose radius is somewhat smaller than the disc.
Demo 05-14 (frame 20059) A ball rolls around a circular hoop with one segment cut out to illustrate the kinematics of an object moving in a circle (28 s). Equipment: Metal ring with short missing section and steel sphere.
Demo 05-15 (frame 20903) Erasers are placed at various radii on a horizontal disc, which is then rotated with a continually increasing angular velocity. The erasers at larger radii slip off the disc first, because a larger centripetal force is required to keep them in place (40 s). Equipment: Sizable disc with concentric circles marked for reference, variable speed rotator and 3 erasers.
Demo 05-16 (frame 22107) A flat disc spins horizontally like a top. When red water droplets are placed on the disc they immediately spin off in a tangential path (16 s). Equipment: Plastic disc, eye dropper, supply of water dyed with food coloring and supply of white paper.
Demo 05-17 (frame 22604) A ball on one end of a rope executes circular motion in a horizontal plane. The other end of the rope passes through a slick vertical tube and is attached to a weight. The weight provides the centripetal force required for the ball to execute circular motion (37 s). Equipment: Rubber ball secured to a string, plastic tubing sleeve and hooked weights.
Demo 05-18 (frame 23727) This demonstration makes use of the contact force between a coin and the end of a coat hanger to hold a coin in place as the hanger is rotated (36 s). Equipment: Coat hanger and supply of coins.
Demo 05-19 (frame 24818) A toy plane is tethered to a long string. When the plane is started in motion, the string makes a small angle with respect to the vertical and the plane flies around in a circle, with the string defining a cone. As the speed of the plane increases, the angle of the cone, and the radius of the plane's circle become larger (37 s). Equipment: Battery powered propeller plane mounted from a high point with a string.
Demo 05-20 (frame 25931) This demonstration illustrates the role of inertia and centripetal force in the operation of a rotating fairground ride. A toy person is positioned against the inside wall of a rotating cylinder. As long as the cylinder rotates rapidly, the person is stuck to the wall by its inertia (44 s). Equipment: Rotating disc, variable speed rotating motor, nonferrous vertical wall attachment, toy person bonded to a disc magnet.
Demo 05-21 (frame 27269) A bucket of water is rotated in a vertical circle. The inertia of the water holds it in the bucket even when the bucket is upside down (33 s). Equipment: Bucket of water.
Demo 05-22 (frame 28277) An elastic hoop is rotated about its diameter so that as the angular speed becomes greater, the hoop becomes more oblate, in a similar manner as the way in which the Earth has become oblate due to its motion (56 s). Equipment: Thin brass hoop mounted on a center rod with top portion free to move and variable speed motor.
Demo 05-23 (frame 29957) This demonstration shows how two liquids of different density, such as milk and cream, can be separated using a centrifuge (40 s). Equipment: Round bottom flask bonded to a rotor mount, colored water, mercury and variable speed motor.
Demo 05-24 (frame 31178) A flexible chain is rapidly rotated on a spinning disc. It is then pushed gently off the disc and it rolls as if it was solid (43 s). Equipment: Motor driven rotor, loop of flat chain, wooden push rod, rectangular piece of rubber sheet and obstacle for loop to jump over.
Demo 05-25 (frame 32466) A rubber wheel with spokes is rotated with increasing angular speed, causing it to stretch to a larger radius. The centripetal force required to maintain the outer circle of the rubber wheel becomes greater with increasing angular speed (32 s). Equipment: Spoked thin rubber, variable speed motor and clamps.
Demo 05-26 (frame 33437) A model of a centrifugal governor is rotated with an increasing angular speed. As the angular speed increases, the weights rise, allowing the mechanism to control its angular speed with the appropriate feedback mechanism (22 s). Equipment: Centrifugal governor and hand rotor.
LD-6: DISK 6
Chapter 13- Rotational Acceleration and Energy
Demo 06-01 (frame 457) Two weights can be positioned symmetrically along an arm that rotates in a vertical plane around its center, varying the moment of inertia of the rotating arm. A weight passing over pulleys of varying radius provides the torque that rotates the arm. The acceleration is shown for several moments of inertia and torques (112 s). Equipment: Angular acceleration machine, 2 concentric driving discs. 2 equal mass cylinders, length of string and driving weights.
Demo 06-02 (frame 3831) A bike wheel is held fixed in space and allowed to rotate about an axis. The external torque that produces rotation is supplied by a rope attached to a spring scale so magnitude of torque may be kept constant (45 s). Equipment: Rim loaded bicycle wheel, long length of string, spring scale, reference mark on wheel rim and clock.
Demo 06-03 (frame 5194) Air is ejected out of a lawn sprinkler device, causing the device to rotate in the expected sense. When deflectors are mounted so that they catch the outgoing air and deflect it in the opposite direction, the device moves with opposite rotation (72 s). Equipment: Rotating lawn sprinkler with added deflectors and supply of compressed air.
Demo 06-04 (frame 7358) A variety of rolling bodies, including spheres, rings, discs, and weighted discs are rolled down an inclined plane to determine the properties of accelerated rolling bodies (86 s). Equipment: Inclined plane, hoop and cylinder of equal mass, 2 equal mass wood cylinders (1 with brass rim, 1 with brass center), 2 spheres with different diameters and sphere and cylinder of equal diameters.
Demo 06-05 (frame 9941) This demonstration illustrates conversion of energy from gravitational potential energy to a combination of rotational and translational kinetic energy when a spool has its large ends touch a table after rolling down an incline on its small central rod (48 s). Equipment: Inclined plane and 2 discs about a central rod to form a spool.
Demo 06-06 (frame 11387) A bicycle wheel is rolled down an incline on a thin axle and the motion is examined (58 s). Equipment: Bicycle wheel, pair of elevated inclined rails and support for the rails.
Demo 06-07 (frame 13133) A spool with large radius ends and a small radius center is wound with a length of ribbon around its center section. An orientation of the ribbon that will slide the spool without rolling is found (43 s). Equipment: Clear plastic spool with central hub and length of wide ribbon.
Demo 06-08 (frame 14423) A spool consists of a thin rod wrapped with string at each end with a heavy concentric disc at the center of the rod. The spool is exhibits motion similar to a yo-yo when released (42 s). Equipment: Large yo-yo and support structure.
Demo 06-09 (frame 15680) A ball is rolled down an incline, performing the loop the loop. For the ball to remain in contact with the incline at all times it must start at a height that will give it sufficient velocity at the top of the track (49 s). Equipment: Piece of U-channel bent into loop the loop configuration, support system and ball.
Demo 06-10 (frame 17156) A horizontal meter stick is loaded with pennies and one end of the stick is released. The pennies will stay on the meter stick only at those points where it has an acceleration less than that due to gravity (41 s). Equipment: Ring stand, clamp and pivot bar, meter stick and supply of pennies.
Demo 06-11 (frame 18402) A stick, hinged at its lower end, has a ball resting on its upper end and a cup mounted near the end. When the stick is released from this position, the ball falls into the cup, showing that the end of the stick has moved downward with an acceleration greater than the acceleration of gravity (34 s). Equipment: A meter stick hinged at one end to a horizontal base with golf tee mounted at other end, plastic cup mounted at desired position to meter stick and a ball bearing or large marble.
Demo 06-12 (frame 19425) A metal bar is suspended at one end by a string. When the bar is struck horizontally, it will oscillate wildly if the blow is far from the center of percussion. If the bar is struck at the center of percussion, it rotates smoothly about the support point (44 s). Equipment: Ring stand, cross bar with hook and clamp, string supported metallic bar and a mallet.
Demo 06-13 (frame 20745) The video shows a Foucault pendulum, and tracks the motion at equal time intervals to determine how the plane of the pendulum rotates (114 s). Equipment: Double knife edge support system, long length of wire, heavy mass bob, supply of short strings and supply of flame.
Demo 06-14 (frame 24155) A planar model illustrating the Coriolis effect can be obtained by rolling a ball across a slowly rotating turntable (52 s). Equipment: Rotating horizontal disc and steel ball.
LD-7: DISK 7
Chapter 14- Conservation of Angular Momentum
Demo 07-01 (frame 478) Marbles are rolled down the inside of a large funnel with their initial velocities directed azimuthally near the top of the funnel. As they roll, their angular speed increases, illustrating conservation of angular momentum (38 s). Equipment: Large glass funnel, marbles or steel ball bearings and a catcher cup.
Demo 07-02 (frame 1630) A wind-up train is allowed to start into motion from rest on a circular track, which in turn is mounted concentrically on a bicycle wheel free to rotate. When the train begins to move the wheel rotates in the opposite direction, conserving angular momentum (28 s). Equipment: Model train track mounted on bicycle wheel and model train locomotive.
Demo 07-03 (frame 2483) The escape wheel in a pocket watch periodically changes its angular momentum as it oscillates, creating an oscillating torque on the watch itself. a laser beam bounces off a small mirror mounted on top of the watch, amplifying the tiny oscillations of the watch (35 s). Equipment: Wind-up pocket watch, plano-convex lens, small piece of tackiwax, small piece of front slivered mirror and a laser.
Demo 07-04 (frame 3528) The demonstrator sits on a stool that rotates on a low friction bearing, holding weights out at arm's length. Upon being rotated the demonstrator moves their arms in and out to increase and decrease the angular speed (36 s). Equipment: Tall stool and a pair of dumbbells.
Demo 07-05 (frame 4621) The demonstrator sits on a rotating stool with low-friction bearings, holding a long bar with weights on each end. When the bar is rotated, the system maintains its initial zero angular momentum, thus causing the demonstrator to rotate in the opposite sense (41 s). Equipment: Tall stool and long bar with 2 sizable weights.
Demo 07-06 (frame 5863) A spinning bicycle wheel is held by the demonstrator, who in turn sits on a rotating stool that is isolated by low-friction bearings. When the angle of the axis of rotation of the rotating bicycle wheel with respect to the vertical is changed, an equal and opposite change is induced in the angular momentum of the demonstrator (38 s). Equipment: Rotational stool and a rim loaded bicycle wheel with handles attached to its axle.
Demo 07-07 (frame 7010) A gyroscope, mounted in gimbal rings, is moved about in space. It remains oriented in the same direction, exhibiting gyroscopic stability (49 s). Equipment: Gimbals mounted gyroscope, securely mounted high rpm motor and clamps.
Demo 07-08 (frame 8483) A bicycle wheel rotating in the horizontal plane is braked by attaching it to a massive frame. When the frame is connected to the rotating wheel, the total moment of inertia increases substantially, leading to a dramatic decrease in the angular speed of the system (54 s). Equipment: Rim loaded bicycle wheel, supply of strings, source of flame and additional weights.
Demo 07-09 (frame 10103) A satellite derotator uses conservation of angular momentum to stop the rotation of a satellite in space. While the system is spinning, 2 massive discs are released, moving to a larger radius and carrying a large amount of angular momentum (72 s). Equipment: Satellite derotator, 2 small clamps, several larger clamps and a start up cord with handle.
Demo 07-10 (frame 12258) A bicycle wheel spinning on a long axle is supported at one end of the axle by a rope. The external torque caused by the force of gravity on the wheel causes it to precess (41 s). Equipment: Rim loaded bicycle wheel with handles mounted on its axle, start up spring and a support cradle.
Demo 07-11 (frame 13500) A small gyroscope is balanced by a weight whose radius can be adjusted. If the weight is positioned on the arm as to unbalance the system, the gyroscope will precess (66 s). Equipment: Gyroscope with adjustable counterbalance system and a start-up motor.
Demo 07-12 (frame 15497) A bicycle wheel is mounted so that it rotates freely on a set of gimbals. Weights are positioned at various points along the extended axle, and the resulting precession observed (92 s). Equipment: Bicycle wheel with loaded rim mounted with large gimbals and fitted with identical pair of extension rods off each end of the axle, each carrying one of a pair of identical weights.
Demo 07-13 (frame 18261) Two identical bicycle wheels are mounted coaxially onto a rigid axle that is supported at one end and the momenta of the wheels is examined when spun in unison (36 s). Equipment: 2 bicycle wheels with collinear axle, large bearing support system, several large clamps and rim markers on each wheel.
Demo 07-14 (frame 19357) A motorized gyroscope is used to illustrate the principles of vector angular momentum and torque. The relation between the direction of the force and the resulting precession is investigated (72 s). Equipment: Motorized gyroscope, length of rod and weight with string loop.
Chapter 16 - Rotational Phenomena
Demo 07-15 (frame 21527) A rotating system is shown to illustrate the difference between static and dynamic balance (63 s). Equipment: Linear analog of a wheel and axle.
Demo 07-16 (frame 23431) A spinning football exhibits dynamical stability when it is spun. If it is spun about its smaller axis, it will rise up and spin about its longer axis (19 s). Equipment: Rubber football and smooth surface.
Demo 07-17 (frame 24020) A tippy top, an asymmetric top with a partial sphere on one end and a stem on the other end, rises so that its heavier end is on top when it is spun with the heavy end down (36 s). Equipment: Tippy top and smooth surface.
Demo 07-18 (frame 25122) A gyroscopic ship stabilizer can be used to stabilize a sailing ship against some of the tipping motions that can be annoying to passengers (41 s). Equipment: Ship analog carrying a motorized gyro disc.
Demo 07-19 (frame 26352) This demonstration illustrates that objects tend to spin in the orientation that gives them maximum moment of inertia about the spin axis (32 s). Equipment: Variable speed electric hand drill, steel cable with solid rod securely clamped to one end and another steel cable with metal hoop in place of the rod.
Demo 07-20 (frame 27322) A rectangular shaped object with all three dimensions is spun and thrown into the air to examine the stability of the spin about each moment of inertia (58 s). Equipment: Rectangular piece of lumber.
Demo 07-21 (frame 29087) A cone is dissected by cutting it along various orientations to show the different shapes made (53 s). Equipment: Wooden cone cut into desired cross sections.
Demo 07-22 (frame 30677) An ellipse can be drawn by fixing two points, looping string about them and tracing with a pen while keeping the string taut (60 s). Equipment: Large paper covered board, loop of string and a pen.
Demo 07-23 (frame 32491) A Cavendish balance is used to determine the value of the universal constant of gravitation (86 s). Equipment: Cavendish balance, laser and a clock.
LD-8: DISK 8
Demo 08-01 (frame 463) Weights are hung on a spring suspended from a fixed point, as an illustration of Hooke's law (83 s). Equipment: Spring, weight hanger, slotted weights, meter stick and spring with different spring constant.
Demo 08-02 (frame 2957) The extension of a spring is compared with the extension of two identical springs in series and in parallel (38 s). Equipment: 2 identical springs, spring scale and a meter stick.
Demo 08-03 (frame 4102) Using a torsion lathe, a metal rod is twisted and the angle of twist measured as a function of the twisting force (85 s). Equipment: Torsion rod, rods of differing materials and diameters, end clamp, weights with hooks and rectangular Lazy Susan.
Demo 08-04 (frame 6662) Springs of copper and brass wire are extended and then released. The brass spring is elastic while the copper spring remains extended (53 s). Equipment: Piece of plastic slinky and 2 springs with made of brass and copper.
Demo 08-05 (frame 8265) Weights are hung from a long wire and the increases in length measured as a function of tension. The extension is measured using the deflection of a laser beam by a mirror that tilts as the wire becomes longer (64 s). Equipment: Young's modulus apparatus, laser and slotted weights.
Demo 08-06 (frame 10193) Three beams of the same material are clamped at one end and loaded by placing weights on the free end. The dependence of the amount of bend on the length of the beam, the cross sectional area of the beam and the amount of weight hung onto the end of the beam are shown (92 s). Equipment: 3 metal beams of same material, but 1 beam is half as long as another and the last beam is twice as thick as the first, hooked weights, support assembly and clamps.
Demo 08-07 (frame 12950) Two "bridges" are formed by rectangular aluminum sheets spanning the space between pillar supports, with one twice the length, width and thickness of the other. Weights are placed on them in the same 2:1 ratio and the displacement from center is shown to be much greater than twice that of the smaller bridge (43 s). Equipment: 2 strips of aluminum, 2 aluminum cylinders and 2 sets of end supports.
Demo 08-08 (frame 14253) Bologna bottles are thick-walled glass bottles that have their outside hardened and their inside very highly strained. The outside of the bottle is used to pound a nail and the inside is barely scratched, yet it shatters the bottle (75 s). Equipment: Safety goggles, bologna bottle, block of wood, nail, gloves and supply of carborundum.
Demo 08-09 (frame 16520) Normally soft or elastic materials become rigid at the temperature of liquid nitrogen, as shown in the demonstration (133 s). Equipment: Supply of liquid nitrogen, glove, strips of flexible rubber, spring fashioned from soft solder, weight, support system for the spring, lead bell, 2 copper tubes and a wooden dowel.
Demo 08-10 (frame 20533) A large tuning fork, with a small light attached to one of the tines, vibrates with a large amplitude of oscillation. When the tuning fork is moved across the screen, the path traced out by the light is a sine wave (31 s). Equipment: "Soft" tuning fork with a small light attached to one tine.
Demo 08-11 (frame 21477) A mass hanging on a spring exhibits simple harmonic motion when displaced vertically from its equilibrium position and released (46 s). Equipment: 2 identical springs, support system, weight hanger, slotted weights, clock and meter stick.
Demo 08-12 (frame 22862) An air track glider is connected by two springs to fixed points at the end of the air track. The glider is made to exhibit simple harmonic motion and the period of the glider is varied (77 s). Equipment: Air track, blower system, glider, 2 identical springs, masses and 2 additional identical springs.
Demo 08-13 (frame 25196) A torsion pendulum executes rotational oscillations subject to the restoring torque of a twisted wire, small rod or spring. In this example, a metal disc, hanging horizontally by its center from the end of a small rod, executes simple harmonic motion (37 s). Equipment: Torsional pendulum, cylinder whose mass is equal to pendulum disc and rim markers to aid visibility.
Demo 08-14 (frame 26327) Pendula with the same length, but different mass are released together so that their periods can be compared (20 s). Equipment: 2 equal length pendula with bobs of identical material, but appreciably different diameters.
Demo 08-15 (frame 26941) Pendula of length ratio 4:1 are released together and their periods compared (32 s). Equipment: 2 pendula with identical bobs, but one having length four times the shorter.
Demo 08-16 (frame 27909) A series of four metal arcs, with angular widths of increasing portions of a circle, are suspended symmetrically from a knife edge, displaced from equilibrium and released. They all execute simple harmonic motion with the same period (46 s). Equipment: 4 metal arcs of equal radii, each a larger section with the last a full circle.
Demo 08-17 (frame 29308) A simple pendulum is released and allowed to oscillate at a variety of amplitudes to explore the relationships inherent to its motion (111 s). Equipment: Pendulum with a large bob and a clock.
Demo 08-18 (frame 32652) A physical pendulum consisting of a rigid bar of aluminum suspended from a point near one end is made to execute simple harmonic motion. The period of the physical pendulum is compared to that of a simple pendulum of varying length (42 s). Equipment: Physical pendulum, simple pendulum and another simple pendulum at only 2/3 the length.
Demo 08-19 (frame 33916) A physical pendulum is mounted rigidly to a bearing such that the angle of the plane in which the physical pendulum swings can be adjusted, and the effect of increasing the angle of the plane of the pendulum is examined (53 s). Equipment: Physical pendulum with massive bob and a bearing pivot point, support system and a Lazy Susan.
Demo 08-20 (frame 35522) This demonstration compares the projection of a spot executing uniform circular motion with the projection in the vertical plane of the motion of an oscillating mass hanging on a spring (30 s). Equipment: Motor-driven rotating disc and the spring and weight carefully chosen so its period of oscillation matches the disc.
Demo 08-21 (frame 36442) This demonstration compares the projection in the horizontal plane of a spot executing uniform circular motion with the motion of a pendulum of the appropriate length (32 s). Equipment: Motor-driven disc and a simple pendulum whose length is carefully adjusted to match the period of revolution of the disc.
Demo 08-22 (frame 37402) Two balls are mounted along the periphery of a rotating disc, which is shadow projected to show the simple harmonic motion of the balls (63 s). Equipment: Motor-driven disc, support system and a light source.
Demo 08-23 (frame 39315) A spring pendulum is driven by a physical pendulum with a frequency different from the normal frequency of the spring pendulum. The resulting motion is complex motion of a non-harmonic oscillator (22 s). Equipment: Massive pendulum, secondary vibrator and something to restrict the motion of the vibrator.
Demo 08-24 (frame 39973) An inertia balance is a device by which two masses can be compared independently of the existence of a gravitational field. The platform is put into horizontal vibration and the motion is described (58 s). Equipment: Platform spring scale, 2 masses with different densities and an inertia balance.
Demo 08-25 (frame 41725) A series of independent simple pendula of monotonically varying length are attached to a rigid support. When displace perpendicular to the support and released, the pendula undergo phase changes such that they create a series of traveling and standing waves (62 s). Equipment: Series of 15 independent simple pendula with identical bobs whose lengths generate the desired apparent progression of identical phase changes and a starting bar.
Demo 08-26 (frame 43608) Lissajous figures are produced on an oscilloscope screen using 2 sinusoidal oscillators (79 s). Equipment: 2 audio oscillators, 4 leads and an oscilloscope.
LD-9: DISK 9
Demo 09-01 (frame 478) A bowling ball, hanging from a long rope, is struck by a mallet at the normal frequency, attaining sinusoidal motion of significant amplitude (50 s). Equipment: Bowling ball pendulum and rubber mallet.
Demo 09-02 (frame 1975) A weight mounted securely on a hanging rod forms a physical pendulum that is coupled to a rocker bar that rotates at the frequency of the physical pendulum. Attached to the bar are 3 independent simple pendula, and when the physical pendulum is given correct period, it can drive one of the simple pendulums (61 s). Equipment: Massive physical pendulum and 3 pendula with bifilar suspension independently mounted to physical pendulum.
Demo 09-03 (frame 3828) A mass on the end of a spring is driven by a mechanical oscillator, and the resulting amplitude of vibration of the mass on the spring can be observed (56 s). Equipment: Spring and weight, variable speed, motor-driven suspension point and motor speed control.
Demo 09-04 (frame 5509) A pendulum model of a child swinging is formed from a mass hanging on a string that passes over a pulley, and the motion is described (66 s). Equipment: Ring stand, clamp and cross bar, clamp and bearing pulley, weight and long piece of string.
Demo 09-05 (frame 7509) A reed tachometer can be used to determine the frequency of a vibrating object A gyroscope gradually slows down, passing through the resonant frequency of the reeds (41 s). Reed tachometer, motor with rubber covered start-up disc and clamps.
Demo 09-06 (frame 8738) Resonant frequency is demonstrated by causing a glass beaker to shatter after exposing it to sound waves (101 s). Equipment: Highly stable audio oscillator, power amplifier, horn driver, foam rubber pad, microphone, oscilloscope and a strobe light.
Demo 09-07 (frame 11766) Two identical physical pendula are coupled by a spring. When one of the pendula is started into motion, the motion will couple through the other spring, and transfer energy back and forth between pendula (118 s). Equipment: 2 physical pendula whose bobs can be adjusted, supporting system and several springs with different spring constants.
Demo 09-08 (frame 15310) A Wilberforce pendulum is set up and the motion described for one complete cycle (76 s). Equipment: Wilberforce pendulum and support system.
Demo 09-09 (frame 17612) Pulses are set up in a stretched rope and allowed to reflect off the fixed end of the rope back to the beginning (22 s). Equipment: Long rope attached to a fixed point.
Demo 09-10 (frame 18286) A chain is driven such that it rotates rapidly around a motor at one end and a pulley at the other. The motion of a pulse is described along the chain (30 s). Equipment: Motor-driven pulley, long length of flat chain, striker bar and 4 clamps.
Demo 09-11 (frame 19192) A transverse pulse is produced in a stretched thin rubber tube, and its speed along the tube is noted (46 s). Equipment: Long length of rubber tubing attached to fixed point at one end.
Demo 09-12 (frame 20576) A wave machine is used to show waves pulses propagating (20 s). Equipment: Wave machine.
Demo 09-13 (frame 21171) Two wave machines are shown, one with shorter rods than the other, and the speed of the pulses along the machines is compared (28 s). Equipment: Wave machine.
Demo 09-14 (frame 22013) Waves are created and propagated along a longitudinal wave model (24 s). Equipment: Longitudinal wave machine.
Demo 09-15 (frame 22749) Rapidly compressing a section of a slinky and releasing it causes propagation of a pulse along the slinky (45 s). Equipment: Slinky with paper flags place every fifth coil to enhance visibility.
Demo 09-16 (frame 24123) Wave pulses are superposed on a wave machine to illustrate how transverse waves are added (54 s). Equipment: Wave machine.
Demo 09-17 (frame 25764) A pulse is reflected off the end of a wave machine and the idea of phase inversion is examined by fixing the reflecting end of the wave machine (42 s). Equipment: Wave machine and end clamp.
Demo 09-18 (frame 27019) A spring produces a wave that is reflected with the end free and fixed, and the motion described (46 s). Equipment: Long brass spring, clamp and bar.
Demo 09-19 (frame 28412) Two different wave machines are connected and the motion of the wave as it travels across the boundary is described (68 s). Equipment: Two different sections of wave machine, interface section and blacklights.
Demo 09-20 (frame 30453) Refraction of water waves in a ripple tank can be seen when the wave fronts pass over a piece of plastic (25 s). Equipment: Ripple tank, rectangular piece of plastic, light source, vibrator system and projection screen.
Demo 09-21 (frame 31208) A ripple tank is used to show the single slit diffraction of waves and that the ratio of the wavelength depends on the slit size (52 s). Equipment: Ripple tank and single slit apparatus.
Demo 09-22 (frame 32768) Double slit interference is shown with a ripple tank and the dependence of the wavelength on the slit separation is examined (48 s). Equipment: Ripple tank and double slit apparatus.
Demo 09-23 (frame 34229) Two transparent slides containing sets of equally spaced circles are superimposed on an overhead projector creating an analog to the double slit interference pattern (24 s). Equipment: Overhead projector and 2 slides with identical concentric circles.
Demo 09-24 (frame 34964) A longitudinal wave machine is used to illustrate standing waves (57 s). Equipment: Longitudinal wave machine and end clamp.
Demo 09-25 (frame 36691) A suspended slinky demonstrates standing waves when oscillated at the resonant frequency, and the pressure nodes and antinodes are marked on the demonstration (42 s). Equipment: Slinky and paper flags to enhance visibility.
Demo 09-26 (frame 37961) The wave machine illustrates standing waves when one end is oscillated at the resonant frequency (37 s). Equipment: Wave machine and 2 blacklights.
Demo 09-27 (frame 39074) Standing waves of different wavelength can be produced in identical strings by vibrating one end of each tube at the same frequency and hanging different masses on the other end (54 s). Equipment: Motor driven can vibrator, 3 lengths of string with one end tied to the vibrator and the other ends passing over 3 pulleys, appropriate masses for the pulleys and several clamps.
Demo 09-28 (frame 40711) A variable frequency motor is used to vibrate the end of a long rubber tube, creating standing waves of various harmonics (96 s). Equipment: Variable speed motor, vibrating assembly, length of rubber tubing, free-wheeling pulley, hooked weight and clamps.
Demo 09-29 (frame 43598) A variable frequency oscillator and a loudspeaker positioned underneath a drumhead are used to excite the resonances in a drumhead. Several modes are shown, including symmetric and antisymmetric modes (52 s). Equipment: Rubber diaphragm, speaker, audio oscillator and strobe light.
Demo 09-30 (frame 45174) A square black anodized aluminum plate is exited in its center by vibrations in the 20 kHz range originating from magnetostriction in a thin-walled annealed nickel tube. Standing waves are formed and the nodal lines are shown (110 s). Equipment: Square, flat black plate attached to a thin-walled annealed nickel tube, support plate with electric coil on underside, audio oscillator, amplifier and supply of sand.
LD-10: DISK 10
Demo 10-01 (frame 459) This demonstration shows the wave shapes produced by plucking various guitar strings on an oscilloscope. The effect of tightening and loosening a string is demonstrated, along with the difference between strings (67 s). Equipment: Guitar, microphone, amplifier, oscilloscope and speaker.
Demo 10-02 (frame 2463) A sonometer string is connected by an electromagnetic pickup to an oscilloscope and standing waves are produced. The effect of tightening, loosening and shortening the string is demonstrated (102 s). Equipment: Sonometer with pulley and heavy weight, 2 long clip leads, impedance matching device, amplifier, speaker, oscilloscope, horseshoe magnet and a bridge for sonometer.
Demo 10-03 (frame 5514) Three tuning forks are sounded and their waves displayed on an oscilloscope (44 s). Equipment: Microphone, amplifier, oscilloscope, 3 tuning forks of differing frequencies and rubber mallet.
Demo 10-04 (frame 6854) The waveform of a large tuning fork with masses attached to the tines is displayed on an oscilloscope, and the pitch of the tuning fork rises as the masses are moved downward along the tines. If masses are at different points along their respective tines, the tuning fork is mistuned and the sound damps out quickly (77 s). Equipment: Adjustable tuning fork, rubber mallet, microphone, amplifier and speaker.
Demo 10-05 (frame 9180) Three types of oscillations are shown on a long aluminum bar: transverse vibrations in horizontal and vertical planes and longitudinal vibrations (61 s). Equipment: 3 foot rectangular aluminum bar firmly mounted at its center and a rubber mallet.
Demo 10-06 (frame 11026) A short aluminum rod held in the middle is struck sharply on the end, producing a high frequency longitudinal oscillation. A shorter rod is struck, making an even higher frequency oscillation (33 s). Equipment: 2 cylindrical aluminum bars and a small wooden mallet.
Demo 10-07 (frame 12019) Notes at one-octave intervals are played in succession on a xylophone, and the waves are displayed on an oscilloscope (49 s). Equipment: Metal xylophone, small wooden mallet, microphone, amplifier and oscilloscope.
Demo 10-08 (frame 13499) Longitudinal vibrations in the audible frequency range can be produced in an aluminum rod by holding the rod at a nodal point and drawing a cloth covered with powdered violin rosin tightly along the rod (90 s). Equipment: 2 long aluminum rods with differing lengths and supply of crushed rosin.
Chapter 24- Properties of Sound
Demo 10-09 (frame 16197) A sound source is activated in a glass chamber and all of the air is pumped out, creating a vacuum, and the sound is no longer heard. When the air is pumped back in, the sound is heard, demonstrating the necessity of a medium for sound (78 s). Equipment: Glass bell jar with an electronic siren, pump plate with batteries and switch for siren, vacuum pump and heavy-walled rubber hose.
Demo 10-10 (frame 18555) The siren disc is a rapidly rotating disc with a large number of holes equally spaced around circles of several radii. When a jet of air is directed onto the passing holes a tone is created whose frequency is the frequency with which the holes pass the air jet (63 s). Equipment: An aluminum disc with concentric rings of regularly spaced, identically drilled small holes in concentric rings (as described above), electric motor and supply of compressed air through a hose.
Demo 10-11 (frame 20440) A rapidly rotating gear can be contacted by a cardboard or plastic sheet to produce a steady state tone using a Savart wheel (35 s). Equipment: Set of 4 toothed gears, each with a differing number of teeth, supported through their center by a common axle, rotator motor and 2 stiff, but still flexible, pieces of plastic sheeting.
Demo 10-12 (frame 21494) A loudspeaker has been cut in two so that the motion of the cone can be easily observed for low frequencies. An animation also shows how the speaker creates sound (45 s). Equipment: Speaker with lateral sections cut away, audio oscillator and 2 leads.
Demo 10-13 (frame 22849) Two identical pipe organs are activated by the same air source, originally producing the same frequency of tone, but as the air to one pipe is heated the resonant frequency rises, leading to beats between the two pipes (60 s). Equipment: 2 identical organ pipes, pyrex glass "T" assembly, supply of compressed air, Meker burner, supply of natural gas and source of flame.
Demo 10-14 (frame 24653) An organ pipe is activated with helium, and the resonant frequency of the pipe rises as it is filled with helium, because the speed of sound in helium is greater than that in air (59 s). Equipment: Organ pipe, supply of compressed air and supply of helium.
Demo 10-15 (frame 26417) A Fourier synthesizer is used to add together various harmonics of 440 Hz to create a square wave and a triangular wave (107 s). Equipment: Fourier synthesizer, 6 long leads and an oscilloscope.
Demo 10-16 (frame 29623) This demonstration illustrates the difference in the spectrum of the vocal sounds oo, as in "moo", and ee, as in "knee". The difference between the formant structure is clearly visible. The frequency at which the vowel is sung is then altered, but the formant remains the same (142 s). Equipment: Apple-computer based real time spectrum analyzer and an audio oscillator.
Demo 10-17 (frame 33890) A properly constructed exponential horn provides the best acoustic coupling between loudspeaker transducer and outside world, and this demonstration illustrates the effect of an exponential horn enclosure (34 s). Equipment: Audio oscillator, 2 clip leads and tweeter horn.
Demo 10-18 (frame 34929) Two tuning forks with slightly different frequencies are sounded simultaneously with approximately the same intensity, producing beats (61 s). Equipment: Two 512 Hz tuning forks, one of which has been trimmed off with new masses added, resonating boxes for each, foam rubber pads and a rubber mallet.
Demo 10-19 (frame 36776) Audio oscillators are used to create beats, which are displayed on an oscilloscope (68 s). Equipment: 2 audio oscillators, impedance matching device, amplifier, load on/off switch, speaker, oscilloscope, and associated leads.
Demo 10-20 (frame 38824) Young's experiment for sound is performed, illustrating that the pattern of nodal and antinodal lines spreads out as the wavelength is increased and becomes closer together as the wavelength is decreased (79 s). Equipment: 2 speakers mounted on a bar and wired in phase, support assembly, audio oscillator and 2 leads.
Demo 10-21 (frame 41196) In this demonstration small speakers are rotated on the end of a boom arm, where the observer is a microphone located on the video camera. A rise in frequency is observed when the speaker is coming toward the camera, and a drop in frequency when moving away from the camera (55 s). Equipment: Rotating Doppler device, 2 very long leads and audio oscillator.
LD-11: DISK 11
Chapter 25- Standing Sound Waves
Demo 11-01 (frame 476) The detailed structure of resonance and standing waves in an acoustical closed end tube is investigated in this demonstration. A closed tube is excited at its open end by a sinusoidal wave from a small loudspeaker, and a plunger with a microphone is moved away from the open end to find nodes and antinodes. The sound signal is also displayed on an oscilloscope (175 s). Equipment: Glass tube with a piston that has a small microphone mounted on it, amplifier, oscilloscope, small speaker mounted at end of tube, audio oscillator, meter stick and appropriate leads.
Demo 11-02 (frame 5746) Three closed tubes are excited by blowing air across the opening at one end of the tube. The frequency of the sound is shown to be related to the length of the tube (35 s). Equipment: 3 glass tubes with equal diameters, but varying lengths, and a supply of compressed air running through a hose with nozzle.
Demo 11-03 (frame 6800) A Kundt's tube uses light powder such as cork dust to render the motion of the air in a standing wave "visible". The cork dust becomes agitated where the air is in motion, and is quiescent at the positions in the standing wave where the air is quiescent (39 s). Equipment: Kundt's tube, supply of fine, dry cork dust, supply of alcohol and a rag.
Demo 11-04 (frame 7992) A tube with one end closed resonates at a frequency approximately one octave lower than an open tube of the same length in the video (49 s). Equipment: A length of tubing, 256 Hz and 512 Hz tuning forks and a rubber mallet.
Demo 11-05 (frame 9456) Three organ pipes are each blown with a cap on the end and without the cap, and the frequency difference is examined (75 s). Equipment: 3 organ pipes with differing lengths and widths, each with a removable end plug.
Demo 11-06 (frame 11725) A slide whistle is a closed tube resonator that produces its sound using edge tones. The closed end of the whistle can be moved in and out to raise or lower the frequency of resonance, as heard in the video (30 s). Equipment: Wooden slide whistle.
Demo 11-07 (frame 12639) Singing pipes are resonant acoustical open tubes that achieve their sound from the noise generated by convection currents. The air in the tubes is heated to produce sound resonance (67 s). Equipment: 2 tin pipes of equal diameter, but differing lengths and open ends, Meker burner, supply of natural gas, source of flame and length of glass tubing with a piece of stainless steel wire mesh embedded in the glass at a position approximately 1/4 its length.
Demo 11-08 (frame 14647) When a tuning fork is sounded and held in the air, the sound is weak due to poor acoustic coupling, but when acoustically coupled to a box of the proper size, sound is much louder, as shown in the video (54 s). Equipment: 2 tuning forks of different frequencies, 2 resonance boxes of appropriate size, rubber mallet and foam rubber pads.
Demo 11-09 (frame 16265) A Helmholtz resonator is a hollow sphere with a large neck and a smaller nipple that can be inserted into the ear to observe the resonant behavior of the resonator. When a tuning fork at the frequency of the resonator is held near the resonator, the sound of the tuning fork becomes louder (66 s). Equipment: 2 Helmholtz resonators of differing sizes, 2 cylindrical supports, 256 and 512 Hz tuning forks and a rubber mallet.
Demo 11-10 (frame 18243) In the video the barometric pressure in a mercury tube is reduced to the pressure of the vacuum pump and then allowed to increase to normal atmospheric pressure (93 s). Equipment: Simple mercury barometer, barometer bell jar, pump plate, vacuum tubing, vacuum pump and vacuum grease.
Demo 11-11 (frame 21027) An aneroid barometer measures the atmospheric pressure by comparing the pressure inside and outside a sealed compartment. In the video, an aneroid barometer is used to measure pressure changes as the demonstrator blows into or sucks on the chamber surrounding the membrane, creating a pressure change (41 s). Equipment: Aneroid barometer with vacuum chamber and rubber tubing.
Demo 11-12 (frame 22257) Two steel hemispheres are positioned together, and the air is pumped out from inside the sphere. The spheres are then held together by a force arising from the air pressure, which is equal to the cross-sectional area of the spheres multiplied by the air pressure (91 s). Equipment: Madgeburg hemispheres, vacuum grease, vacuum tubing, vacuum pump, tall ring stand, clamp and bar, S hooks, weight hanger, slotted weights and foam rubber pad.
Demo 11-13 (frame 25008) This demonstration illustrates the force of cohesion between two glass plates. Two glass plates are carefully cleaned and pressed together. The plates hang tightly together (39 s). Equipment: Adhesion plates.
Demo 11-14 (frame 26183) This demonstration uses air pressure to crush a can by pumping all the air out of the can (52 s). Equipment: Gallon can, one-hole rubber stopper, vacuum tubing, vacuum pump and piece of metal tubing.
Demo 11-15 (frame 27741) The air is pumped out of a tube, the ends of which have been sealed with loose sheets of metal, and a ball is placed in one end of the tube adjacent to the seal. When the seal is knocked off with a mallet, the force of the atmospheric pressure, and the lack of air pressure on the other side of the ball, accelerate it out the end of the tube (52 s). Equipment: Long length of metal pipe with square cut ends and equipped with a vacuum port for vacuum tubing, dead weight, flat end cover plates with bonded rubber sheets for sealing, vacuum grease, vacuum tubing, vacuum pump, rubber ball and a target.
Demo 11-16 (frame 29319) In this very dramatic demonstration of air pressure, a 55 gallon barrel is crushed by atmospheric pressure. Water is boiled in the barrel to fill it with steam and water vapor. The barrel is then sealed and cooled with ice. When the steam condenses, its volume shrinks by a factor of about 1000, reducing the pressure within the barrel dramatically. The external air pressure is then sufficient to crush the barrel (81 s). Equipment: 55 gallon barrel, 4 gallon cans, 4 Meker burners, supply of natural gas, source of flame, supply of water, gloves, plugs for barrel openings, wrench and supply of crushed ice.
Demo 11-17 (frame 31756) This video demonstrates pressure distribution through a confined fluid, Pascal's Law. A subject stands on a board that has been placed on top of a hot water bottle. Blowing air from the experimenter's mouth into a tube connected to the hot water bottles provides sufficient pressure and upward force to lift the subject (30 s). Equipment: 2 hot water bottles, large board, bottle plugs, rubber tubing and a glass or metal "T" mouthpiece.
Demo 11-18 (frame 32675) A long thin board is placed on a table with about half of the board extending over the edge of the table. The section of the board on the table is then covered with a sheet of newspaper. The end of the board is hit with a sharp blow, breaking the board (17 s). Equipment: Wooden shingles or shim stock, flat pieces of paper and solid table edge.
Demo 11-19 (frame 33201) The atmospheric pressure of air is used to lift a chair in this demonstration. A thin sheet of rubber, attached in the center to a handle, is placed tightly on the seat of a chair. When the handle is grasped firmly and lifted, the atmospheric pressure keeps the rubber in contact with the chair, and the chair is lifted (26 s). Equipment: Chair, thin flexible rubber sheet, weight hanger and a short metal bar.
LD-12: DISK 12
Demo 12-01 (frame 459) This demonstration shows that water "seeks its own level". A system of connected tubes is at equilibrium when the water is at the same height in each tube (25 s). Equipment: Equilibrium tubes and supply of colored water.
Demo 12-02 (frame 1218) This video shows that the pressure in a liquid is proportional to the depth of the liquid. The demonstration uses a pressure sensitive transducer connected to an array of light-emitting diodes that make a bar graph of the pressure (55 s). Equipment: Tall cylinder of water, length of plastic tubing and an LED display electronic pressure gauge with a pressure sensor located in the tip of the bar.
Demo 12-03 (frame 2863) The apparatus of 12-02 is used to compare the pressure of a column of water with the pressure of an identical column of alcohol. The pressures at the same depth in alcohol and water are compared in the video (56 s). Equipment: Demo 12-02 apparatus and a supply of alcohol.
Demo 12-04 (frame 4551) A large membrane on the end of a tube is lowered into a tank of water, showing that the pressure in the tank increases with a distance below the surface. When the membrane is rotated so that it faces any arbitrary direction, the pressure remains the same, verifying that the pressure at any point in a fluid is independent of direction (48 s). Equipment: Manometer, length of rubber tubing attached to a rubber stopper of appropriate size to fit the manometer, clear plastic cell with one side covered by rubber dental dam sheeting, and equipped for attaching the rubber tubing and a large clear container of water.
Demo 12-05 (frame 5988) A syringe filled with air can be easily compressed by a force on the plunger of the syringe. When the syringe is filled with water, it cannot be compressed (47 s). Equipment: Large syringe, large weight and supply of colored water.
Demo 12-06 (frame 7399) Water is poured into one side of a U-tube originally partially filled with mercury. The equilibrium level of the water is higher than the level of the mercury in the other side of the U-tube, due to the difference in their densities, as shown in the video (31 s). Equipment: Tall, U- shaped mercury manometer, support system including meter stick and squeeze bottle nozzle and colored water.
Demo 12-07 (frame 8327) A hydraulic press uses Pascal's law for the pressure in a confined fluid to convert a small force into a large force. A small force is exerted on a small area piston, creating a large force on the large piston (65 s). Equipment: Hydraulic press, supply of wooden blocks and supply of metal bars.
Demo 12-08 (frame 10277) A glass plate can be held against a truncated glass cone submerged in water by the hydrostatic pressure of the water. If the tube does not have a large enough area, the net force provided by the water is insufficient to hold the plate up, as shown in the video (47 s). Equipment: Truncated glass cone with ground glass ends, flat piece of glass and clear container of water.
Demo 12-09 (frame 11700) In the video the hydrometer is placed first in water and then in alcohol, in which it floats more deeply and thus gives a smaller density (31 s). Equipment: Hydrometer, tall clear cylinder of water and tall clear cylinder of alcohol.
Demo 12-10 (frame 12650) A hollow sphere is weighed on a pan balance. The air is then pumped out of the sphere and it is again weighed on the balance. An additional mass is added to compensate for the lost air (77 s). Equipment: Platform balance mounted on a ring stand, round bottom flask fitted with a rubber stopper, vacuum tubing, vacuum pump and 1 g weight.
Demo 12-11 (frame 14959) The video shows that the loss of weight of a submerged object is equal to the buoyant force. A weight hanging on a spring balance is lowered into a container of water which is hanging from a second spring balance to show the relation (82 s). Equipment: 2 large spring scales, weight, clear container of water and weight hanger.
Demo 12-12 (frame 17411) As a large weight, hanging from a spring scale, is lowered into a water bath, the displaced water is collected in a glass beaker to show that Archimedes principle is in effect (88 s). Equipment: Tall ring stand, clamp, short bar, hook, spring scale, small bucket, weight with hook, large clear container of water with spillover spout and rubber stopper and a catch basin.
Demo 12-13 (frame 20061) A long balsa board is inserted into a tall cylinder of water and a series of weights are then added to the lower end of the board to show the board submerges by a constant amount each time (53 s). Equipment: Long board of balsa wood, tall clear cylinder of water and 3 weights.
Demo 12-14 (frame 21651) Three types of wood, of increasing density, are floated in a water tank. The fraction of the wood block that is submerged is equal to its specific gravity, as shown in the video (42 s). Equipment: 3 blocks of wood with identical dimensions, made of balsa, pine and iron, and a transparent container of water large enough to float all 3 blocks at once.
Demo 12-15 (frame 22923) A density ball is used to show how a ball will float in water depending upon the temperature of the water (52 s). Equipment: Ring stand, ring clamp, pyrex beaker, density ball, water, Meker burner, supply of natural gas and source of flame.
Demo 12-16 (frame 24480) A steel ball is put in a beaker of dry beans. When the beaker is shaken the ball will sink to the bottom and a light ping-pong ball that was on the bottom will float to the top (30 s). Equipment: 2 large beakers of dry beans, ping-pong ball and a heavy steel sphere.
Demo 12-17 (frame 25390) In this video a rectangular block of wood with a square cross section is floated in a square plastic container in a very small amount of water (46 s). Equipment: Clear container whose geometry closely matches that of the wood, water and a block of wood.
Demo 12-18 (frame 26790) Three liquids of different density are poured into a cylindrical tube and form layers of mercury, carbon tetrachloride and water. In this video, samples of three materials of different density are dropped into the liquids and each will float in one of the liquids (51 s). Equipment: Tall clear cylinder, mercury, carbon tetrachloride, water, cylinder of iron, cylinder of bakelite and wooden dowel rod.
Demo 12-19 (frame 28330) A symmetric long square bar floats in water with its sides at angles that depend on the specific gravity of the bar. This is shown by adding water to an alcohol bath with the bar in it (82 s). Equipment: Transparent float, clear tank, alcohol and water.
Demo 12-20 (frame 30784) A helium balloon floats at the top of an inverted glass jar. When the jar is also filled with helium the balloon floats near the mouth of the jar. When the helium is allowed to escape, the balloon again floats upward (60 s). Equipment: Large clear container, balloons, helium gas and 3 blocks to elevate inverted container.
Demo 12-21 (frame 32599) A helium balloon is drenched in liquid nitrogen to show how the buoyant force is related to changes in volume (43 s). Equipment: Balloons, helium gas, liquid nitrogen, string and a hooked weight.
Demo 12-22 (frame 33901) The cartesian diver, which contains some air within its volume, normally floats at the top of a water bath, but when the pressure is increased inside the water tube using a hypodermic syringe, the air in the diver is compressed, allowing additional water to flow into the bottom of the diver container. This illustrates buoyancy (87 s). Equipment: Cartesian diver and water bath.
LD-13: DISK 13
Demo 13-01 (frame 476) A pitot tube is used to measure the velocity of a moving air stream (31 s). Equipment: Pitot tube with attached all-glass manometer, air blower with hose and a variac.
Demo 13-02 (frame 1427) A Flettner rotor uses the Magnus effect to create a force on a rotating drum in an external air stream, as shown in the video (54 s). Equipment: Flettner rotor and a large fan.
Demo 13-03 (frame 3058) Examples of balls that curve when thrown are shown in the video, and the explanation of the magnus effect is given (43 s). Equipment: Light Styrofoam ball and a throwing tube cut from a cardboard mailing tube.
Demo 13-04 (frame 4357) In the video a Styrofoam ball is suspended in the air stream from a vacuum cleaner (37 s). Equipment: Styrofoam ball, air blower with hose and variac.
Demo 13-05 (frame 5479) An air stream is moved radially outward between a fixed horizontal plate and a second plate which is held close to the first plate. The rapidly moving air reduces the pressure between the plates, holding the two plates together. In the video weights are hung from the plates (31 s). Equipment: Flat metal disc, heavy ring stand, 2 right angle clamps, cross bar, 1 or 2 paper streamers taped to edge of disc, length of rubber tubing, supply of compressed air, second flat disc with a hook screw mounted in center and a weight hanger with slotted weights.
Demo 13-06 (frame 6419) A rapidly moving air stream is injected between two plastic sheets. The difference in pressure pushes the cards together (14 s). Equipment: 2 stiff cardboard squares, length of rubber tubing and a supply of compressed air.
Demo 13-07 (frame 6838) A vortex cannon is used to create a circular vortex of air. The process used to generate this ring is demonstrated and the motion of the fluid within the circular vortex (48 s). Equipment: Large metal cylinder with an end cap that has a relatively small hole in it and the other end is capped with rubber sheeting, set barrel on rectangular Lazy Susan, smoke generator, supply of cigarettes, source of flame, candle and lab jack.
Demo 13-08 (frame 8275) This demonstration dramatically illustrates laminar fluid flow by injecting colored dye in a layer of glycerin between two cylindrical shells. When the inner cylinder is rotated in one direction the dye is mixed, but when rotated the other way the dye unmixes back to its original shape (111 s). Equipment: Beaker of water, supply of dye or ink, spoon or string rod, unmixer as described in video, supply of glycerin, syringe with long needle and supply of dyed glycerin.
Demo 13-09 (frame 11610) Two plastic bottles are joined at the nozzles and an amount of water is in one of the bottles. The bottles are overturned draining the water into the unfilled bottle, but the bottles are spun to generate a vortex, facilitating drain (60 s). Equipment: 2 two-liter plastic bottles and plastic coupling.
Demo 13-10 (frame 13431) A siphon is used to show how water flows between containers to attempt to keep the water levels at equilibrium (73 s). Equipment: 2 large beakers, supply of colored water and a length of clear plastic tubing.
Demo 13-11 (frame 15631) A syringe is used to show that when a fluid flows through a large cross section to a smaller one, the speed of the fluid increases (50 s). Equipment: Supply of colored water, large syringe, ring stand, right angle clamp and three-fingered clamp.
Demo 13-12 (frame 17137) Water flowing uniformly along a tube that is connected to several sensing tubes shows that pressure drops uniformly along the tube (58 s). Equipment: One horizontal piece of glass tubing and 3 vertical pieces of glass tubing, 3 brightly colored wooden dowels to float in vertical tubing, rubber tubing, and a supply of water.
Demo 13-13 (frame 18895) Water flowing along a tube with a constriction at its center is used to demonstrate Bernoulli's principle (59 s). Equipment: Glassware similar to demo 13-12, 3 brightly colored floats, paper sleeve to temporarily cover center vertical tube, rubber tubing at both ends of the glassware and a supply of water.
Demo 13-14 (frame 20659) The operation of a water hammer is done to show how a mass of water that is stopped suddenly can generate sound (31 s). Equipment: Water hammer.
Demo 13-15 (frame 21585) Water squirts out holes put in a tall water tank to show that the trajectory of the water is greatest at the hole in the center of the tank (44 s). Equipment: Vertical glass tube with 4 lateral outlets, support system, tubing, supply of water and large catch basin.
Demo 13-16 (frame 22916) A light ball is tethered in a jar of water, as is a heavy ball in its jar. The light ball is tethered at the bottom of the jar, the heavy ball at the top, and when the jars are accelerated the balls move in opposite directions (35 s). Equipment: 2 quart jars filled with water, one with a heavy ball and the other with a light one.
Demo 13-17 (frame 23959) In the video the shape of the surface of a water container is viewed as the container is set into rotation and the water assumes its equilibrium shape (35 s). Equipment: Clear cylinder with a rotary mount on its end cap, variable speed rotary motor and a supply of water.
Demo 13-18 (frame 25005) In this video two thin water troughs are rotated on a turntable, one of which is straight and runs radially outward from the center of the turntable, and one which is circular and runs along the outer circumference of the turntable. The shape of the water in the trough is then examined (38 s). Equipment: A circular disc supporting a circular, narrow walled transparent trough mounted on the opposite side of the disc along a diameter that bisects the circular trough, circular Lazy Susan and supply of colored water.
Demo 13-19 (frame 26148) A disc connected to a limp spring that is lowered onto a water surface is used to show the effect of surface tension (39 s). Equipment: Flat glass disc attached to a spring and clear container of distilled water.
Demo 13-20 (frame 27334) A metal sheet can be floated on the surface of water by carefully placing the sheet on the water without breaking the surface of the water (70 s). Equipment: Large clear container of distilled water, a block of wood, flat stiff sheet of metal with rounded corners, pair of tweezers and several small weights.
Demo 13-21 (frame 29453) A soap bubble is formed with a movable wire held near the ends of a wire frame. When the movable wire is released, the surface tension in the soap bubble pulls the wire up (22 s). Equipment: Square U-shaped wire frame with a slider wire whose ends are loosely looped around the legs of the frame and a container of soap solution.
Demo 13-22 (frame 30135) A variety of soap films are created to show that the bubble assumes a shape to minimize its potential energy (62 s). Equipment: 4 plastic frames of differing geometric forms and a container of soap solution.
Demo 13-23 (frame 31992) Two soap bubbles are connected by a tube to show that if air can pass freely between them the small soap bubble will get smaller, while the large bubble gets larger, a result of surface tension (93 s). Equipment: A glass "T" arrangement with a stopcock in each segment, a short length of rubber tubing for blowing bubbles and a supply of soap solution.
Demo 13-24 (frame 34782) A thread with a loop is attached in the middle of a large wire frame. After the wire frame is immersed in a soap bubble solution, the film is punctured inside the loop of thread, causing the surface tension of the film to pull the thread into a circular shape, minimizing the energy (34 s). Equipment: Square wire framework that has a string loop loosely tied on opposite sides, container of soap solution and a sizable needle-like probe.
Demo 13-25 (frame 35810) A thin tube is inserted into a container of water to demonstrate capillary action caused by the attraction of water molecules to the inside of the glass surface (22 s). Equipment: Glass tube with small inside diameter and a supply of colored distilled water.
Demo 13-26 (frame 36470) A set of four connected capillary tubes are filled with water to show that capillary action is greater for a smaller tube, thus making the water rise higher (31 s). Equipment: Set of interconnecting capillary tubes with differing inside diameters, supply of distilled colored water and a syringe for injecting the water slowly.
LD-14: DISK 14
Demo 14-01 (frame 462) Two objects are released simultaneously and allowed to fall to the floor. The object with less air drag arrives first, due to the viscosity of the air (34 s). Equipment: Several pieces of paper. Demo 14-02 (frame 1492 Three balls are dropped into a tall cylinder of glycerin and allowed to drop to the bottom of the cylinder. The balls quickly reach terminal velocity, due in part to the viscous drag of the glycerin on the balls (45 s). Equipment: Tall glass cylinder of glycerin, glass ball, steel ball and lead ball.
Demo 14-03 (frame 2860) This demonstration is designed to extract measurements of acceleration of gravity and drag coefficient by analysis of data on the disc (54 s). Equipment: Tall ladder, superball, wood ball, golf ball, 3 Styrofoam balls of varying diameters, 2-meter stick and a stopwatch.
Demo 14-04 (frame 4494) The demonstration shows how viscosity of a heated gas can effect the size of the flame it produces (52 s). Equipment: Double burner "T" with each end turned vertically upward, supply of natural gas, source of flame, separate Meker burner and 2 lengths of rubber tubing.
Demo 14-05 (frame 6067) A demonstration of the viscosity of alcohol as it is cooled with liquid nitrogen by passing it through a cloth screen (61 s). Equipment: Supply of alcohol, ring stand supporting a ring clamp covered with cloth, a ring stand, test tube clamp and test tube located at the height appropriate for the dewar, catch basin and a dewar of liquid nitrogen.
Demo 14-06 (frame 7903) This video shows the difference in viscosity between three weights of motor oil as a demonstration in the viscosity of fluids (50 s). Equipment: 3 long glass tubes, each containing oil of different viscosity and sealed, leaving an air bubble of equal size in each.
Demo 14-07 (frame 9410) A wire is tightly stretched horizontally between two points. When an electrical current is passed through the wire, it expands and sags, showing thermal expansion (65 s). Equipment: Long iron wire tautly suspended, small hooked weight, height indicator, paper flags to aid visibility and a variac.
Demo 14-08 (frame 11361) A bimetallic strip is heated to show it bend one way, and then placed in liquid nitrogen to bend it the other way, a demonstration of the difference in expansion coefficients in metals (86 s). Equipment: Bimetallic strip, Meker burner, length of rubber tubing, source of flame, dewar of liquid nitrogen, bimetallic coil with a pointer and a hotel pad.
Demo 14-09 (frame 13935) A bimetallic strip is used as a thermostat to show expansion and contraction of a metal. The strip makes electrical contact with a light when cool, but after contact the light heats the strip so that it bends away from the contact point and turns off the light, starting the whole cycle over again (60 s). Equipment: Bimetallic strip, Meker burner, length of rubber tubing, source of natural gas, source of flame and a bimetallic strip thermostat model, with switch and light bulb.
Demo 14-10 (frame 15734) Thermal expansion in a rod is used to break a steel pin. This behavior is extended to a discussion of bridges and the expansion joints built into them (72 s). Equipment: Iron rod, threaded on one end with a hole to accommodate a steel pin, burner tube to run below iron rod, supply of quenched steel pins, pair of large locking nuts to secure the steel pin to the framework, length of rubber tubing, supply of natural gas, source of flame and a small mallet.
Demo 14-11 (frame 17913) A discussion is conducted around whether a ball, which can not initially pass through a metal hole, is able to after the hole is heated (48 s). Equipment: Piece of square brass plate with a center hole, supply of natural gas, source of flame and a brass sphere whose diameter is slightly larger than the hole.
Demo 14-12 (frame 19353) This demonstration shows that air expands as it is heated by having a flask of air grasped firmly, thereby expanding the air and pushes the water level in a connected flask downward.
Demo 14-13 (frame 20562) The expansion of a liquid when heated demonstrates the concept behind a liquid filled thermometer (44 s). Equipment: Water thermometer made by filling a round bottom flask with colored water and connecting it to a manometer, Meker burner, length of rubber tubing, supply of natural gas and a source of flame.
Demo 14-14 (frame 21876) A pyrex beaker is completely filled with water at 0° C. As the temperature of the water increases, the height of the water column decreases until about 4C, and then begins to rise again. This illustrates that the density of water is greatest at 4C (78 s). Equipment: Water thermometer (as in demo 14-13), sizable ice bath, thermometer and a cradle for the flask when removed from the ice bath.
Demo 14-15 (frame 24231) This demonstration illustrates a dust explosion when lycopodium powder is blown into a flame. The surface area of the powder readily burns in the proximity of the flame (49 s). Equipment: Supply of lycopodium powder, source of flame, glass funnel clamped to a ring stand with a long length of rubber tubing attached to its stem, candle clamped several inches above the funnel's mouth and appropriate safety gear.
Demo 14-16 (frame 25710) This video shows how the ratio of surface area to volume is increased when an object is broken into small pieces (39 s). Equipment: 27 small cubes stacked into a larger cube of 3x3x3 dimensions with outer surface area painted black.
Demo 14-17 (frame 26896) The specific heats of three materials are compared after being heated to 100C and placed into identical water baths. The temperature rise of the water baths are compared (113 s). Equipment: 75 g of lead shot, 75 g of aluminum chips, 75 g of steel shot, 3 soda cans, boiling water bath for all 3 cans, Meker burner, length of rubber tubing, supply of natural gas, source of flame, 3 Styrofoam cups and a sensitive thermometer.
Demo 14-18 (frame 30289) The specific heats of three metals, aluminum, steel and lead, are compared by allowing equal masses of hot rods of the metals to melt wax (77 s). Equipment: 3 cylinders of aluminum, steel and lead having equal mass and equal diameters, slanted and slotted guide covered with thin layer of beeswax, boiling water, Meker burner, length of rubber tubing, supply of natural gas, source of flame, sizable pair of tweezers and a pair of gloves.
Demo 14-19 (frame 32618) Water is shown to boil in a paper cup because the kindling point of the paper is a higher temperature than the boiling point of water (51 s). Equipment: Supply of paper cups, ring stand, ring clamp, supply of water and source of hot flame.
Demo 14-20 (frame 34146) Flame applied to a balloon filled with air will rupture the balloon, but if filled with water the balloon will not, because the water sufficiently cools the balloon (34 s). Equipment: Balloons, source of flame and water.
Demo 14-21 (frame 35175) This demonstration compares the heat conductivity for several materials by melting wax along a rod made of either steel, glass, brass, aluminum or copper (83 s). Equipment: 5 identical rods of glass, brass, steel, aluminum and copper extended outward from a common steam reservoir, each dipped in molten paraffin, 2 lengths of rubber tubing, steam generator and source of heat.
Demo 14-22 (frame 37659) The Leidenfrost phenomenon is illustrated by dropping water on a hot skillet and liquid nitrogen on a table top and showing the thin layer of steam between the liquid and surface (48 s). Equipment: Stove or hot plate, skillet, water and supply of liquid nitrogen.
Demo 14-23 (frame 39099) A radiometer is used to show how a vane coated in black will rotate away from a source of light (29 s). Equipment: Radiometer and lamp.
Demo 14-24 (frame 39975) This demonstration illustrates the difference between thermal radiation properties of black and shiny objects. The blackbody is shown to both absorb more efficiently and radiate more efficiently (93 s). Equipment: 2 identical metal cans with caps, each with a hole, but one black and the other shiny, 2 thermometers and supply of hot water.
Demo 14-25 (frame 42779) The radiation cube illustrates the difference between radiation from various surfaces at the same temperature (89 s). Equipment: Leslie cube, rotating support stand, hot water supply, thermopile detector, galvanometer and pair of gloves.
Demo 14-26 (frame 45458) This demonstration shows the effectiveness of various dewar flasks for keeping hot water hot (97 s). Equipment: 4 dewar flasks (1 evacuated with dual mirror coating, 1 evacuated with no mirror coating, 1 mirror coating but no vacuum, and 1 with no mirror coating or vacuum), rack to support dewars, boiling water, 4 thermometers and gloves.
Demo 14-27 This demonstration has video problems.
LD-15: DISK 15
Chapter 34- Laws of Thermodynamics
Demo 15-01 (frame 474) This demonstration shows the conversion of mechanical energy to heat by rotating a wooden dowel into a block of wood using an electric drill (38 s). Equipment: Piece of board with preset dimples, foot long piece of wooden dowel rod with one end somewhat rounded, electric drill and a short piece of wooden dowel rod that can fit into electric drill.
Demo 15-02 (frame 1616) Lead shot is allowed to fall from one end of a tube to another, gaining potential energy which is converted to kinetic energy, and then to heat. This causes a rise in temperature measured on a thermistor (50 s). Equipment: 1 meter long clear plastic tube loaded with lead shot, one end of which has a thermistor in it, and a LED readout for the thermistor.
Demo 15-03 (frame 3110) A fire extinguisher is used to show how CO2 cools when it evaporates by freezing water in a test tube (26 s). Equipment: CO2 fire extinguisher and test tube filled with water.
Demo 15-04 (frame 3906) This demonstration illustrates the adiabatic expansion and cooling of air, and the concomitant production of fog due to the cooling of the air below its dew point (79 s). Equipment: Bottle of carbonated soft drink, bottle opener, clear gallon bottle with a small amount of water with a thermistor suspended midway, bicycle pump and appropriate rubber stopper with penetration tube and clear plastic tubing.
Demo 15-05 (frame 6268) A fire syringe consists of a small tube with a plunger sealed by O-rings, which can be used to rapidly compress air in the tube, raising its temperature adiabatically (45 s). Equipment: bicycle pump, bicycle tire, fire syringe, supply of cotton and wire ramrod.
Demo 15-06 (frame 7627) The operation of a small Stirling engine is shown in the video to illustrate the Stirling heat cycle (68 s). Equipment: Stirling engine, engine fuel and source of flame.
Demo 15-07 (frame 9684) A Hero's engine is operated using steam from a boiling water bath to rotate a flask and nozzle system, illustrating the principle of action and reaction as applied to a "rotational rocket" (34 s). Equipment: Glass Hero's engine, water, Meker burner, length of rubber tubing, supply of natural gas and a source of flame.
Demo 15-08 (frame 10709) This demonstration shows the conversion of mechanical energy into heat with a rotating corked container of water and two pieces of wood which are squeezed around the container (55 s). Equipment: see demo 15-07.
Demo 15-09 (frame 12351) This demonstration shows the enormous increase in volume when a liquid evaporates into a gaseous state with liquid nitrogen and a balloon (69 s). Equipment: Large, round bottom pyrex flask, supply of liquid nitrogen, gloves and a single hole stopper with a balloon pulled over the end.
Demo 15-10 (frame 14413) Reducing the pressure in a beaker of water can cause the water to boil at a reduced temperature and pressure (86 s). Equipment: Round bottom flask with a deep dimple in its bottom, ring stand, 2 ring clamps, C-clamp, water, Meker burner, length of rubber tubing, supply of natural gas, source of flame, rubber stopper fitted with a thermometer, supply of ice and gloves.
Demo 15-11 (frame 16991) The boundary between liquid and gaseous states is clearly shown as the temperature of carbon dioxide passes the critical point in a tube. Above the critical point the two states fuse and the boundary disappears (95 s). Equipment: Thick walled glass tube containing liquid carbon dioxide at 80 atm of pressure and a hair dryer.
Demo 15-12 (frame 19849) A toy drinking bird shows a cycle of condensation and evaporation that makes the toy bob back and forth (50 s). Equipment: Toy drinking bird, water and small lab jack.
Demo 15-13 (frame 21346) The atmospheric pressure above a small sample of water is greatly reduced, causing the water to boil. The evaporation of the water boiled off requires heat, which is provided by the remaining water bath, so the water bath cools and eventually freezes (58 s). Equipment: Crystallization dish with an elevated watch glass of smaller diameter than the dish- the dish holds acid and the glass holds the water and a few boiling beads, supply of concentrated sulfuric acid, water, pump plate, supply of silicone vacuum grease, bell jar, length of vacuum tubing and vacuum pump.
Demo 15-14 (frame 23092) Cooling by evaporation is demonstrated by using a cryophorus placed in a container of liquid nitrogen (33 s). Equipment: Cryophorus, pyrex beaker and dewar of liquid nitrogen.
Demo 15-15 (frame 24098) The ice bomb demonstrates the expansion of water as it freezes. An iron sphere is filled with water, sealed and placed in a bath of liquid nitrogen, breaking the iron sphere (183 s). Equipment: Ice bomb, source of water, wrench, half-gallon milk carton with top removed, thick-walled 5 gallon paint can, dewar of liquid nitrogen, thick, wide board and 2 lead bricks.
Demo 15-16 (frame 29593) The phenomenon of regelation is shown with a weight attached to wires passing through a piece of ice (54 s). Equipment: Block of ice, loop of small diameter stainless steel wire and a catch basin.
Demo 15-17 (frame 31227) This experiment illustrates the change in volume of a gas due to changes in temperature, and the change in state of a gas as it passes its transition temperature, using balloons filled with helium and carbon dioxide (103 s). Equipment: Flat Styrofoam container, dewar of liquid nitrogen, balloon filled with helium, scissors, balloon filled with carbon dioxide and forceps.
Demo 15-18 (frame 34311) This experiment shows the enormous change in the volume of a material as it changes state from a gas to a liquid or solid using a carbon dioxide balloon immersed in liquid nitrogen, showing sublimation (81 s). Equipment: Low profile Styrofoam container, supply of liquid nitrogen, balloon filled with carbon dioxide, gloves and scissors.
Demo 15-19 (frame 36747) A slime ball is used to show how under normal atmospheric pressure it has small viscosity and flows readily, but under high pressure it behaves like a rubber ball (40 s). Equipment: A commercially available product called "Slime".
LD-16: DISK 16
Demo 16-01 (frame 463) This demonstration uses a movable plunger in a calibrated tube and a pressure gauge to illustrate Boyle's Law: PV = constant (48 s). Equipment: Boyle's law apparatus, overhead projector and screen.
Demo 16-02 (frame 1903) A hollow sphere filled with air is connected to a pressure gauge. Data points are taken on the video at the temperature of boiling water, room temperature and ice water to show how pressure and temperature are related (57 s). Equipment: Hollow copper sphere connected to a pressure gauge, overhead projector, screen, ice water, boiling water, ring stand and ring clamp, Meker burner, length of rubber hose, supply of natural gas and a source of flame.
Demo 16-03 (frame 3633) The molecular motion of a gas is simulated by using small metal spheres to represent atoms of a gas (34 s). Equipment: Molecular motion demonstration, leveling platform, overhead projector and screen.
Demo 16-04 (frame 4654) The dependence of pressure and temperature is demonstrated by using small metal balls to simulate gas molecules. The volume of the container is decreased, thus increasing the pressure in that volume (41 s). Equipment: see Demo 16-03, but with a bar with magnets on its ends so the total length fits just inside the vibrating framework.
Demo 16-05 (frame 5890) This demonstration uses two sizes of metal spheres to simulate gases of various molecular weight to show that all the balls develop the same kinetic energy, thus making the small balls travel faster (32 s). Equipment: see Demo 16-03, but with small and medium plastic spheres.
Demo 16-06 (frame 6855) Heated mercury atoms develop a great deal of kinetic energy, as shown when small bits of glass float on mercury in a sealed test tube. As the mercury is heated, the energetic mercury vapor causes bits of glass to jump about wildly (25 s). Equipment: Enclosed glass tube containing colored glass chips and small amount of mercury, ring stand and test tube clamp, Meker burner, length of rubber tubing, supply of natural gas and source of flame.
Demo 16-07 (frame 7606) A microscope is used to view the collision of smoke particles with air particles, thus exhibiting Brownian motion (29 s). Equipment: Microscope, smoke cell fitted with a squeeze bulb on one side and a cork on the other side, light source and matches.
Demo 16-08 (frame 8484) Small metal balls are used to illustrate gas molecules, and if a large disc is placed in the simulator along with the balls, the disc will move about as the small spheres strike it. This provides an analog to Brownian motion with smoke particles in air (27 s). Equipment: see Demo 16-03, but with a large plastic disc.
Demo 16-09 (frame 9305) The diffusion process is illustrated on the video for methane gas and helium in a porous clay jar (80 s). Equipment: Porous clay jar, 3 lengths of rubber tubing, source of natural gas, source of helium and source of compressed air.
Demo 16-10 (frame 11725) Diffusion through a porous material is demonstrated using a molecular motion simulator and a baffle with a small hole. Small molecules readily pass through, but large ones do not (48 s). Equipment: see Demo 16-03, but with a baffle with a small hole.
Demo 16-11 (frame 13178) The diffusion of molecules through a gas is shown with two tubes containing bromine, one is partially evacuated and the other containing air. The air will slow down the diffusion process (52 s). Equipment: Two glass tubes, one containing bromine only and the other with bromine and air, ring stand, 2 right-angle clamps, 2 three-fingered clamps and dry ice/alcohol bath (or a dewar of liquid nitrogen).
Demo 16-12 (frame 14744) A Gaussian curve is illustrated by dropping small metal spheres through a maze of pegs (28 s). Equipment: An array of steel pins located above a series of vertical columns, both situated below a funneling chamber that feeds balls into the array of pins, overhead projector and screen.
Demo 16-13 (frame 15587) The molecular model is used to illustrate the concept of free expansion by removing a barrier and allowing the balls to travel in the full volume (21 s). Equipment: see Demo 16-03 with a solid dividing bar.
Chapter 37 - Crystals and Low Temperatures
Demo 16-14 (frame 16225) The demo shows the levitation of a tiny rare earth magnet over a high-temperature superconductor (39 s). Equipment: Superconducting kit and a supply of liquid nitrogen.
Demo 16-15 (frame 17409) This demonstration shows crystal models of sodium chloride, calcium carbonate and carbon, in the form of graphite and diamond (61 s). Equipment: Crystal models made from various sizes of wooden spheres and metal rods.
Demo 16-16 (frame 19262) A monolayer of metal spheres forms a simulation of a crystal, with each sphere representing one of the lattice sites in the crystal. When the crystal is formed by shaking the spheres and allowing them to settle, fault lines appear (30 s). Equipment: Calcite crystal, model fabricated by separating two sheets of glass around all edges and then loading with a high number of metal spheres, and a shadow project with overhead projector and screen.
Demo 16-17 (frame 20178) The properties of a thermistor are shown by measuring the resistance of the thermistor at different temperatures (48 s). Equipment: Thermistor, 2 clip leads, multimeter with ohm meter capacity and a cup of ice water.
Demo 16-18 (frame 21642) A thermoelectric junction uses the temperature difference across a boundary of two different conductors to generate a large electric current. This is shown by using a thermoelectric junction to power a large magnet which holds up heavy weights (66 s). Equipment: Large thermocouple, ice water, Bunsen burner, length of rubber hose, supply of natural gas, source of flame, thermocouple face plate with hook, weight hanger and several slotted weights.
Demo 16-19 (frame 23618) In this demonstration, a current is passed through a thermoelectric junction, cooling one side of the junction and heating the other. Heat can be passed across a thermoelectric junction (50 s). Equipment: Thermoelectric heat pump, battery eliminator, 2 electrical leads, 2 thermometers and 2 aluminum blocks fitted to accommodate thermometers.
Demo 16-20 (frame 25127) The two metals in a thermocouple can be chosen such that the voltage generated is a function of the temperature of the junction. Such a thermocouple can be calibrated and used to measure temperature, as shown in the video (28 s). Equipment: Large thermocouple, lecture table galvanometer, Meker burner, length of rubber tubing, supply of natural gas and a source of flame.
Demo 16-21 (frame 25983) An acrylic and rubber rod are used to show that charges of opposite sign attract while charges of the same sign repel (76 s). Equipment: An acrylic rod, rubber rod, wool cloth and a bearing pivot system.
Demo 16-22 (frame 28262) This demonstration illustrates the existence of residual charge by showing the force betwe