coin rotation paradox (original) (raw)

coin rotation paradox Visualisation of the coin rotation paradox for general coin radii by CMG Lee. A coin of radius ''r'' rolls around one of radius ''R'' = 3''r''. In (1), if ''R'' is straightened out, the number of rotations (number of times the arrow points upwards) is ''R''/''r'' = 3. In (2), as ''R'' has been restored into a circle, ''r'' makes an extra rotation, giving ''R''/''r'' + 1 = 4. 1. 2. 1 2 3 1 2 3 4