Introduction to Elastic and Inelastic Collisions

An elastic collision is defined as a collision where objects bounce off one another. Momentum is always conserved in any collision. In an elastic collision, kinetic energy is also conserved. Examples include collisions between billiard balls, air-hockey pucks, and atomic particles.

In an inelastic collision, momentum is conserved, but kinetic energy is not conserved. The loss of kinetic energy is due to the deformation of the objects, which converts kinetic energy into thermal energy. It's important to carefully distinguish between 'elastic' and 'inelastic' when discussing kinetic energy conservation.

A specific type of inelastic collision is a 'perfectly inelastic collision' (also known as totally or completely inelastic). In this type, objects collide and stick together. Examples include football tackles and railroad cars coupling together.

A demonstration with two bouncing balls illustrates inelastic collisions. Since neither ball returns to its original drop height, kinetic energy is not conserved, indicating both are inelastic collisions. The ball that bounces lower converts more kinetic energy into thermal energy.

All real-world bounce collisions are fundamentally inelastic, as some kinetic energy is always converted to thermal energy due to deformation, even in cases like billiard balls. While atomic-level collisions can be elastic, macroscopic elastic collisions are considered ideal cases and are never fully achieved in reality.