Identifier:
M: CM - 009
Concept Overview
Forces in vertical circular motion.
Lecturer Procedure
| Steps to Follow | Expected Result |
|---|---|
| Quarter will fall off - this will show that the surface is not sticky. |
| Quarter will remain attached to the hanger until motion is slowed such that the quarter will fall off. |
Note:
This demonstration requires lecturer practice prior to doing in front of the students. 5-10 minutes should be sufficient.
Historical References; Taken from original work of Percy H. Carr, 1970
“A [quarter] is placed on a coat hanger and rotated in a vertical circle of radius 0.2 m. The minimum speed occurs when the push of the coat hanger on the penny is zero at the highest point. Then g=v2/r, whence v = square root of rg. In the demonstration the value of r is approximately 20 cm = 0.2 m. The minimum speed of the [quarter] is then the square root of (9.8 m/s2)(0.20 m), or 1.4 m/s.”
Video Demonstration
Tutorial:
Set-up Instructions for M: CM - 9
Transcript:
There is no audio with this recording.