This is a demonstration of the conservation of angular momentum using a Hoberman sphere, a plastic sphere frame that can be contracted by pulling on a string. Pulling on the string while the sphere is rotating causes the sphere’s moment of inertia to decrease and its angular speed to increase, demonstrating conservation of angular momentum.

It was created at Utah State University by Professor Boyd F. Edwards, assisted by James Coburn (demonstration specialist), David Evans (videography), and Rebecca Whitney (closed captions), with support from Jan Sojka, Physics Department Head, and Robert Wagner, Executive Vice Provost and Dean of Academic and Instructional Services.

[Physics Demo | Via TA]