Euler's Disk Available Upon Request

Euler's Disk is a scientific educational toy, used to illustrate and study the dynamic system of a spinning disk on a flat surface (such as a spinning coin), and has been the subject of a number of scientific papers. The apparatus is known for a paradoxical dramatic speed-up in spin rate as the disk loses energy and approaches a stopped condition. This phenomenon has been studied since Leonhard Euler in the 18th century, hence the name.