Question

1. Our text has made a distinction between two different types of collisions according to whether kinetic energy is also conserved or not. Elastic collisions are said to conserve the total kinetic energy, while inelastic collisions result in some loss of energy. Provide and describe a real-life example of each type. Indicate where you think the lost energy went to for your inelastic example.

Answer 1

Elastic collision: In these collisions, the kinetic energy of a system is conserved.

Example: The collision between two billiards ball in a pool game.

When the two balls collide in a pool game. During collision part of kinetic energy is stored as potential energy of the balls, which is again converted back to the kinetic energy of the balls as they separate. No energy is lost.

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Inelastic collision: In these collisions, the kinetic energy is not conserved.

Example: The collision between a car with a wall.

Consider a collision of a car with a wall, the car is moving towards a wall. It collides with the wall and it stops after the collision.

The car was moving before the collision but it stops moving after the collision. Hence all of the kinetic energy of the car is lost.

The lost energy is converted to the heat, sound, and deformation of the car.