### Introduction

The collision of two carts on a track can be described in terms of momentum conservation and, in some cases, energy conservation. If there is no net external force experienced by the system of two carts, then we expect the total momentum of the system to be conserved. This is true regardless of the force acting between the carts. In contrast, energy is only conserved when certain types of forces are exerted between the carts.

Collisions are classified as elastic (kinetic energy is conserved), inelastic (kinetic energy is lost) or completely inelastic (the objects stick together after collision). Sometimes collisions are described as super-elastic, if kinetic energy is gained. In this experiment, you can observe elastic and inelastic collisions and test for the conservation of momentum and energy.

### Objectives

• Observe collisions between two carts, testing for the conservation of momentum.
• Measure energy changes during different types of collisions.
• Classify collisions as elastic, inelastic, or completely inelastic.