Always topical and quite addictive this classic traditional desk toy is a well known stress reliever and still in great demand today. A typical Newton's cradle, named after Sir Isaac Newton, is a device that demonstrates conservation of momentum and energy via a series of swinging spheres. When one on the end is lifted and released, the resulting force travels through the line and pushes the last one upward. See Newton's laws of motion for further information. 144x138x119mm / 5.66"x5.43"x4.68".