Elastic Collision

A collision occurs when two objects come in direct contact with each other. There are two types of collisions namely Elastic Collision and inelastic Collision. An elastic collision is one where there is no net loss in kinetic energy in the system as the result of the collision. An inelastic collision is a type of collision where this is a loss of kinetic energy. The lost kinetic energy is transformed into thermal energy, sound energy and material deformation. Here, in this article, let us learn more about the elastic collision.

What is Elastic Collision?

When two bodies collide but there is no loss in the overall kinetic energy, it is called a perfectly elastic collision. Basically, in the case of collision, the kinetic energy before the collision and after the collision remains the same and is not converted to any other form of energy. It can be either one-dimensional or two-dimensional. In the real world, perfect elastic collision is not possible because there is bound to be some conversion of energy, however small.

However, though there is no change in the linear momentum of the whole system, there is a change in the individual momenta of the involved components, which are equal and opposite in magnitude and cancel each other out and the initial energy is conserved.

Elastic Collision

Examples- When a ball at a billiard table hits another ball, it is an example of elastic collision. Similarly, when you throw a ball on the ground and it bounces back to your hand, there is no net change in the kinetic energy and hence, it is an elastic collision.

Difference between Elastic and Inelastic Collision

 Collision - Elastic & Inelastic Collision

Elastic Collision

Inelastic Collision

The total kinetic energy is conserved.

The total kinetic energy of the bodies at the beginning and the end of the collision is different.

Momentum does not change.

Momentum changes.

No conversion of energy takes place.

Kinetic energy is changed into other energy such as sound or heat energy.

Highly unlikely in the real world as there is almost always a change in energy.

This is the normal form of collision in the real world.

An example of this can be swinging balls or a spacecraft flying near a planet but not getting affected by its gravity in the end.

Example of inelastic collision can be the collision of two cars.

The collision time affects the amount of force that an object experiences during a collision. The greater the time over which the collision occurs, the smaller the force acting upon the object. Thus, to maximise the force experienced by an object during a collision, the collision time must be decreased. Likewise, to minimise the force, the collision time must be increased. There are several real world application of this phenomena. The airbags in automobiles increase the collapse time and minimize the effect of force on objects during collision. Air bag accomplishes this by extending the time required to stop the momentum of the passenger and the driver.

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