For perfectly elastic body, the value of co-efficient of restitution is

Concept:

The energy dissipation during impact is described by the term coefficient of restitution, which is a scalar quantity.

e = velocity of separation / velocity of approach

e = (v₁ - v₂) / (u₂ - u₁)

where, v = velocity of the body after impact, u = velocity of the body before impact

• For perfectly elastic collision, e = 1
• For inelastic collision, e < 1
• For perfectly inelastic collision, e = 0

Note:

When two bodies collide, they exchange energy. The body with higher initial energy transfers some of it to the one with lower energy. Hence, the body with initially higher velocity will have lower velocity after the impact.