What makes some collisions elastic and others inelastic?

Responses

If the collision involves sticking together, it is elastic.

If the collision involves sticking together, it is elastic.

If the collision involves bouncing, it is elastic.

If the collision involves bouncing, it is elastic.

If there is energy lost in the collision to sound, heat, etc., the collision is elastic.

If there is energy lost in the collision to sound, heat, etc., the collision is elastic.

If there is no loss of kinetic energy in the collision, it is elastic.

If there is a loss of kinetic energy in the collision, it is inelastic.