Bicycle wheel, 9 volt battery with Velcro, LED unit
battery with LED unit closeup on wheel

 

Code Number: 1D10.20

Demo Title: Bicycle Wheel - Cycloid Generator

Condition: Excellent

Principle: Reference Frames

Area of Study: Mechanics

Equipment: 

Bicycle Wheel, 9-volt battery with Velcro, LED unit for 9-volt battery.

Procedure: 

Using Velcro, attach the 9-volt battery with LED unit onto the rim of the bicycle wheel.  In a darkened room, you will see that in the reference frame of the bicycle wheel, the LED moves in a circle.  However, if you role the wheel along the lecture bench, you will see that the LED describes a cycloid when looked at from the benches reference frame.

References:

  • Roger Blickensderfer, "The Wheel and the Galilean Transformation",  TPT, Vol. 26, # 3, p. 160, March 1988. 
  • Peter L. Tea, Jr., "On Seeing Instantaneous Centers of Velocity", AJP, Vol. 58, # 5, May 1990, p. 495.
  • Charles T. P. Wang, "Problem: Motion of a Rigid Body On a Cycloid Track", AJP, Vol. 50, # 12, p. 1178, Dec. 1982. 
  • S- 020: "Tractor on Paper-Chalk in Hoop", DICK and RAE Physics Demo Notebook.
  • Paul Wallich, "LED Candles",  Popular Science, August 2006, p. 83.