What experiment demonstrates the conservation of momentum?

The Newton's Cradle experiment is a classic demonstration of the conservation of momentum.

Newton's Cradle is a device that consists of a series of identical metal balls suspended in a frame so that they are just touching each other. When one ball on the end is lifted and released, it strikes the next ball and comes to a stop. The momentum from the first ball is transferred through the line of balls and causes the last ball to swing out. When the last ball swings back and hits the others, the momentum is transferred back down the line, causing the first ball to swing out. This process repeats, creating a continuous swinging motion.

This experiment demonstrates the principle of conservation of momentum, which states that the total momentum of a closed system is constant if no external forces are acting on it. In the case of Newton's Cradle, the system is the line of balls. The momentum of the first ball is transferred through the line and causes the last ball to swing out with the same momentum. When the last ball swings back and hits the others, the momentum is transferred back down the line to the first ball. This shows that the total momentum of the system remains constant.

The Newton's Cradle experiment is a simple yet effective way to visualise the conservation of momentum. It provides a clear demonstration of how momentum is transferred within a system and how the total momentum of a system remains constant if no external forces are acting on it. This principle is fundamental to our understanding of how objects move and interact in the physical world.