Newton's Cradle

This device is one of the simplest yet most effective demonstrations in physics. It consists of steel spheres suspended side by side at equal height. When one or more spheres are lifted and released, the energy and momentum from the collision are transferred in a chain reaction to the other spheres. As a result, the same number of spheres on the opposite side begin to move with equal speed. This is a clear example of Newton’s Third Law: “Every action has an equal and opposite reaction.”

The device also visually demonstrates the conservation of energy and momentum. During observation, it becomes evident that the motion gradually stops — explained by air resistance and heat loss. Despite its simple structure, Newton’s Cradle effectively illustrates fundamental principles of mechanics.

In physics, the law “Every action has an equal and opposite reaction” was scientifically formulated in the 17th century by Isaac Newton. The first mathematical pendulum-type devices showing collisions and energy transfer were developed in the 16th–18th centuries by scientists such as Edme Mariotte and Christiaan Huygens.

The modern term “Newton’s Cradle” was coined in 1967 by British actor Simon Prebble, who introduced the device to the market through his company, Scientific Demonstrations Ltd.