Newton’s Cradle

This is a **Newton's cradle**. It is also known as **Newton's balls** or **Executive ball clicker**. The model illustrates the three main physics principles at work: **conservation of energy, conservation of momentum and friction**.



*When two objects collide, the total momentum of the objects before the collision is equal to the total momentum of the objects after the collision.*



When the first ball of Newton's Cradle collides with the second, the first ball stops, but its momentum is transferred to the second ball, then the third, then the fourth, until it reaches the very last ball. The last ball swings into the air with nearly the same momentum as the first ball.  Thus, if two balls are lifted into the air on one end of the device and released, then two balls on the opposite end will swing in response.