PURPOSE: Demonstrate conservation of angular momentum for a collapsing and expanding sphere.

DESCRIPTION: Suspend the Hoberman sphere and pulley assembly. Start it turning in the open position. Pull on the lower string to collapse the sphere and note how the sphere spins much faster. The string can be released to let the sphere expand again.

EQUIPMENT: Hoberman sphere, large ring stand, and large rod

SETUP TIME: 15 minutes

KEYWORDS: conservation of angular momentum Hoberman sphere