Final answer:
In physics, collisions refer to the interactions between objects that result in a change in their momentum. Collisions can be classified as elastic or inelastic, depending on whether kinetic energy is conserved. In an elastic collision, both momentum and kinetic energy are conserved, while in an inelastic collision, only momentum is conserved.
Step-by-step explanation:
In physics, collisions refer to the interactions between objects that result in a change in their momentum. When two cars collide, for example, there is a transfer of momentum between them. In an ideal collision, total momentum is conserved, meaning that the sum of the initial momenta of the two objects is equal to the sum of their final momenta.
Collisions can be classified as elastic or inelastic. In elastic collisions, both momentum and kinetic energy are conserved, while in inelastic collisions, only momentum is conserved.
For example, when two cars collide and bounce off each other without any energy loss, it is an elastic collision. On the other hand, if the cars stick together after the collision and some kinetic energy is lost as heat or sound, it is an inelastic collision.