Materials Required:
- Wire clothes-hanger
- Coin
Procedure:
- In one hand, hold a wire clothes- hanger by the hook. With your other hand, pull straight down on the bottom wire at the middle. Bend the wire until the hanger has stretched lengthwise and an angle has formed.
- Slip this newly-formed bottom
angle over your index finger and allow the hanger to hang freely. (The hook will now be at the bottom.) - Carefully balance a coin on the tip of the hook. Slowly, swing the hanger back and forth on your finger. Then build up a little speed and spin the hanger in a full circle. Continue spinning as fast as you like. The coin will not fall off.
- When you want to stop spinning, do it gradually, coming to a slow halt. The coin still remains perched, as
if it had been glued to the spot. If
you have trouble on your first try, practise a few times and you will soon be an expert.
This is what happens:
While the hanger is spinning, the tip of the hook exerts an inward force, which pushes the coin towards the centre of the circle. This force is called centripetal force and prevents the coin from flying outward.
