Newton's cradle is a device that demonstrates conservation of momentum and energy using a series of swinging spheres. ... The last sphere swings back and strikes the still nearly stationary spheres, repeating the effect in the opposite direction.
Newton's cradle five-ball system in a 3D two-ball swing
The device is named after 17th-century English scientist Sir Isaac Newton.
SIZE: Size of the black one:19*18*11CM. Size of the silver one:18*11.5*18.5cm