Newton's anti-stress balls are a mechanical system invented by Isaac Newton to present a clear example of the law of energy conversion. Newton's balls are 5 metal spheres suspended on a fishing line, they are used as an anti-stress. You take one ball to the side, release it, and watch the balls on the opposite side begin to move in a mirror image at the same speed. After a certain time, the balls stop. The duration of the movement depends on the size and weightballs: the heavier and larger the balls, the longer the process, and vice versa.
Newton's Antistress Balls are a good way to relax and calm your nerves.