M-D1: For a given Force, acceleration decreases as mass increases

PIRA: Unknown

Equipment: Spring-driven toy auto, 3 500g slotted masses. The equipment is located in Set 9, Cabinet 3, Shelf 1.

Procedure: Wind the spring of the auto to the limit but do not force. Set car on the table and release. Note the acceleration but do not trouble to measure it. Stop the auto and carefully drag it backwards to the starting position so that the spring is thereby rewound to the original tension. Place one 500-gram mass in the truck very nearly over but slightly forward of the rear wheels and release. Note the acceleration is obviously less than before.

Repeat with 2 500-gram masses in the truck, and finally with 3 500-gram masses. It is important to keep the load in the truck nearly over but just forward of the rear wheels. At this highest suggested load the acceleration is quite small but still noticeable. (It is not wise to load to the stall point or point of no acceleration; too many explanations will be required).

When the experiment is complete, carefully let the spring run down while the drive wheels are braked by hand to avoid injury to the motor. See note on the care of auto in M-K1.

Note: If the toy auto will not move even though it has been wound, it could be that one of the wheels is catching on the auto's body. Give the catching wheel a gentle twist and the auto should move.