PURPOSE: To demonstrate how both kinetic energy and linear momentum must be conserved in elastic collisions.

DESCRIPTION: To start, hold one, two, three, or four balls to the side and release. Symmetric oscillations result from conservation of energy and linear momentum in the collision sequence.

SUGGESTIONS: This demo maybe done on a overhead projector in a large classroom. Just set the newton's cradle on the projector.

EQUIPMENT: Newton's Cradle, as photographed.

SETUP TIME: None.

KEYWORKDS: conservation of energy conservation of linear momentum