Newton Cradle Balance Balls -conservation of momentum and energy

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.

Example here: 

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

• MATERIAL: Durable ABS base, nylon strings, stainless steel frame and ball.

• APPLICABILITY: You can put it on your office desk or your home desk or on your shelf. It will be cool desk toy

• FUNCTION: Use it to waste time, relieve stress, tune out boring coworkers, or schooling youngsters in physics.

• OWN YOUR GIFT: Own your special piece of science and explore significant values of physics!