Elastic Collisions

There is no law of conservation of kinetic energy—If kinetic energy is conserved in a collision, it is called an elastic collision, but there is no physical law that requires this.

Typically occurs when you have colliding objects which are very hard or bouncy. An elastic collision is one in which the sum of the kinetic energy of all the colliding objects before the event is equal to the sum of the kinetic energy of all the objects after the event.

Kinetic energy is conserved in an elastic collision