Rolling Circle

The (green) diameter of the circle can be adjusted by dragging its top point up or down.
When the Start button is clicked, the circumference of the circle becomes red and the circle starts to roll.
As the circle rolls, its (red) circumference unwinds and is left behind, taking about 10 seconds for a complete revolution.
After completely unwinding it delays for 5 seconds, rewinds for 10 seconds, delays for another 5 soconds then starts again.

Created by Zen Biker Maniac using GeoGebra.   Java Animator class by H-P Ulven.