Rattle Back

Demonstrate Newton's three laws of motion with the flick of a finger!

Due to its offset center of gravity this scientific curiosity has a preferred direction of rotation it wants to spin counterclockwise. Its spin bias is so strong that when it is spun clockwise, it will turn through a few rotations, stop, rattle (or rock up and down on its long axis), then automatically reverse itself and spin counterclockwise. The Rattleback is so unique that it has been written about in Scientific American.