Question

Show that if their mases are same, velocities interchange after collision

Answer 1

Answer:

If the kinetic energy is the same, then the collision is elastic. If the kinetic energy changes, then the collision is inelastic regardless of whether the objects stick together or not. In either case, for collisions with no external forces, momentum is conserved.

Answer 2

A perfectly elastic collision just means the total amount of kinetic energy is conserved. Further, Newton's laws tell us momentum must be conserved. Any velocity change following a collision is therefore dictated by the mass of the two bodies, their velocities and the application of those two conservation rules.