Elastic and Inelastic Collisions

Collisions: An Overview

Collisions are everywhere — two billiard balls striking each other, a bat hitting a ball, or even molecules bouncing inside a gas. In every collision, the total momentum of the system is always conserved, provided no external force acts during the brief interaction. But what about kinetic energy? That is where the story splits.

The book introduces two fundamental categories: elastic collisions, where kinetic energy is also conserved, and inelastic collisions, where some kinetic energy is transformed into other forms (heat, sound, deformation). A perfectly inelastic collision is the extreme case where the colliding objects stick together and move as one. …