Can newtons cradle balance balls swing forever

newtons cradle balance balls is a tabletop demonstration device invented in the 1860s. Five balls of the same mass are held by slings and are closely arranged with each other. There is a problem with newtons cradle balance balls in actual condition: a moving ball behaves as it Its mass seems to be concentrated in its geometric center. In ideal newtons cradle balance balls, the metal balls are exactly the same mass and will collide perfectly.

What newtons cradle balance balls do is simple harmonic motion, and in ideal conditions, simple harmonic motion consumes no energy, so it can swing forever. It can stop because the mechanical energy is gradually lost due to the resistance of the air during the swing. So, the bigger the newtons cradle balance balls, the more resistance it has, the faster the mechanical energy is consumed, the easier it is to stop and the shorter the swing time.