Coefficient of restitution
The coefficient of restitution (COR, also denoted by e), is the ratio of the final to initial relative speed between two objects after they collide. It is also defined as the ratio velocity of separation to velocity of approach.
The value is almost always equal to 1or less than 1 due to initial translational kinetic energy being lost to rotational kinetic energy, plastic deformation, and heat. Mathematically
Coefficient of restitution (e)= Velocity of separation/Velocity of approach. Coefficient of restitution is always =1<1. Coefficient of restitution was postulated and developed by Sir Isaac Newton.
Range of values for e - treated as a constant
e is mostly a positive, real number between 0 and 1:
e = 0: This is known as perfectly inelastic collision. It implies that kinetic energy along the common normal is 0. Kinetic energy is converted to heat or work done in deforming the objects.
0 < e < 1: This is a inelastic collision, in which some kinetic energy is dissipated. It can also achieve both in practical and in mathematical calculation.
References
Materials science
Mathematics
Mechanics