Newton's Cradle as a timeless classic. The ball-throwing pendulum is not only a classic decorative object for the office or desk, but it also provides interesting insights into physics and the law of conservation of momentum. Simply pull back one or more of the outer balls and let them collide with the stationary balls – on the opposite side, the same number of balls will swing into motion. Looking for a suitable gift for curious adults and little explorers? Then the ball game is a great idea.