the coefficient of restitution is introduced by eulier

the coefficient of restitution for the perfectly plastic body is zero(0).

the coefficient of restitution for the perfectly elastic body is one(1).

The coefficient of restitution is how you quantify bounciness or give bounciness a number, and you do that by dividing the bounce height by the drop height, then finding the square root of that. When you have more bounces you can find more than one coefficient of restitution!

0.54 TO 0.58

With a plastic impact, the coeffecient of restitution is 0.

With an elastic impact, the coeffecient of restitution is 0<e<1.

With an inelastic impact, the coeffecient of restitution is 1.