Newton's Cradle

Newton's cradle, named after Sir Isaac Newton, is a device consisting of a series of pendulums (usually five) abutting one another that illustrates the conservation of momentum and energy. Each ball is attached to a frame by two strings of equal length and angle. One or more balls are moved to hit the others, causing the movement of the same number of balls on the other side. The cradle has been a popular toy and is sometimes used to present Newton's third law of "action-reaction".