An elastic collision is a type of collision in which the total kinetic energy and momentum of the colliding objects remain constant throughout the collision. This means that no energy is lost or gained during the collision, and the objects bounce off each other without sticking together.

In an elastic collision, the following conditions must be met:

* The total kinetic energy of the system before the collision is equal to the total kinetic energy of the system after the collision.

* The total momentum of the system before the collision is equal to the total momentum of the system after the collision.

* The objects collide and then bounce off each other without sticking together.

Elastic collisions are often studied in physics because they are relatively simple to understand and analyze. They can also be used to model more complex collisions, such as those that occur in car accidents or sports.

Here is an example of an elastic collision:

Two billiard balls collide head-on with equal speeds. After the collision, the balls bounce off each other and move away with the same speeds that they had before the collision.

In this example, the total kinetic energy of the system is conserved because the balls have the same speeds after the collision as they did before the collision. The total momentum of the system is also conserved because the balls move away from each other with the same speeds that they had before the collision. Finally, the balls do not stick together after the collision.

Therefore, this collision is an example of an elastic collision.