The Newton’s cradle is a device that demonstrates the conservation of momentum and the conservation of energy with swinging spheres. When one sphere at the end is lifted and released, it strikes the stationary spheres, transmitting a force through the stationary spheres that pushes the last sphere upward.

You can manipulate it below. Click, hold and move away one of the black spheres below the blue spheres. Then, click in the Play button to start the animation. You can pause it or stop it whenever you want. To change the speed of swinging spheres, move the cursor Speed.