1D50.45 - Penny on a Coat Hanger
To show centripetal force.
Get the bent coat hanger and a penny.
Hang the bent coat hanger from your index finger with the hook nearest the floor. Carefully balance a penny on the end of the hook. Spin the coat hanger around your finger in a vertical circle.
The centripetal foce created by the hook on the penny will keep the penny firmly attached to the hook as the aparatus is being spun. Be careful not to bump the hanger while in motion, or the penny will become dislodged. If the class is quiet, they can listen for the sound of a dopped penny. With practice, the penny can be brought to rest while still balanced on the hook. If sucessful, to prove the penny is not glued to the hanger, a quick flick of the hanger will send the penny to the floor.