1D50.45 Coin on a Coathanger
Forces in circular motion
A coin is balanced on the hook end of a coathanger. When the coathanger is swung in a full circle, the coin does not fall off. Note: this demonstration is appropriate for large lecture halls.
-  Coin
-  Swing made from a stretched coathanger
- This demonstration requires a lot of advance practice. Confidence and a smooth motion are requried.
- Place your finger in the bend of the coathanger opposite to the hook.
- Carefully balance the coin on the hook of the coathanger.
- Swing the coathanger vertically, starting with a low amplitude and working up to large amplitudes.
- Continue to increase the amplitude of the swing until the coathanger swings in a full circle.
- PIRA 1D50.45
- Video Encyclopedia 05-18
- J. Dixon "A Penny for your Thoughts" TPT4, 38 (1966)
- G.W. Ficken "Putting a penny into orbit" AJP40(5), 776 (May 1972)
- P. Salmons "The penny and the coathanger" TPT15(1), 46 (Jan 1977)
- A variation, in which the coin is balanced on the long edge of an undistorted hanger, is described by Sutton M-155 and Miller p63
- Don't attempt this at home!
- The coathanger was stretched to form a diamond shape with one bend directly opposite the hook. The end of the hook was filed flat.
- Any coin can be used. A penny works well.
If you have any questions about the demos or notes you would like to add to this page, contact Ricky Chu at ricky_chu AT sfu DOT ca.