Metal Arts Brum:
A collision is an isolated event in which two or more bodies (colliding bodies) exert relatively strong forces on each other for a relatively short time. The g-force can be very large during a short time.

Collisions involve forces (there is a change in velocity). Collisions can be elastic, meaning they conserve energy and momentum, inelastic, meaning they conserve momentum but not energy, or totally inelastic (or plastic), meaning they conserve momentum and the two objects stick together.

The magnitude of the velocity difference at impact is called the closing speed.

The field of dynamics is concerned with moving and colliding objects.