# The Correlation Between Momentum, Collisions and Kinetic Energy

When a collision occurs a force acts upon an object in a given amount of time changing the object’s velocity. Impulse is known as being the product of force and time. When a collision occurs, the impulse encountered by an object is equal to the momentum change it experiences. In a collision with two objects, an interaction of force must occur. This force acts between the objects for some amount of time creating impulse which changes the momentum of each object. While each individual piece that is a part of a collision undergoes a different amount of momentum, the total momentum of the system remains constant.

Momentum describes things that are on the move. It can be defined as “mass in motion.” So, if an object is moving, then it has momentum. However, the amount of momentum depends on how much stuff is moving and how fast it is going; mass and velocity. If, lets say, a car and a truck collide, momentum will always be conserved. However, there are three different kids of collisions. Kinetic energy is what distinguishes collisions when they occur.

The first is elastic collision. This is the only collision in which kinetic energy is conserved; when kinetic energy is not lost. Elastic collision is when colliding objects rebound without lasting deformation or the generation of heat. For example, if a moving billiard ball comes to rest after hitting a second billiard ball, the second billiard ball with move with the speed of the colliding ball. While a small amount of friction is lost, it is still described as an elastic collision.

The second type of collision is inelastic collision. In inelastic collision, kinetic energy is not conserved. It is characterized by deformation, or the generation of heat, or both. The kinetic energy has essentially been changed to some other form of energy in a collision. In a perfect inelastic collision, both objects stick together. For example, if there happen to be two freight trains, and one crashed into the other, they will both share the same momentum after collision.

The third, and rarest type of collision, is completely inelastic collision. In this collision kinetic energy is not conserved, and the colliding objects stick together after the collision. When the maximum amount of kinetic energy of a system is lost, a perfect inelastic collision occurs. This is the only collision in which kinetic energy is lost by bonding the two bodies together.