Euler's Disk

A Captivating Energy Demonstration. If you've ever watched a coin spinning on a tabletop, then you've got to see Euler's Disk. Constructed of heavy metal and a smooth concave surface, this device elegantly demonstrates conservation of energy and angular momentum. Just give the disk a twist and watch it spin and roll for an amazingly long time! Can your students explain why the disk rotates for so long, or why it rotates faster as it gets closer to the surface? Explanations can range from simple statements of energy conservation to complex physics equations such as the work of Leonhard Euler (Oiler), for whom the disk is named. Mirror is 9 inches in diameter!