When two objects, such as two cars or two balls, come into contact and exert forces on each other, we describe this event as a collision. In physics, collisions can be categorized into different types based on how the total kinetic energy of the system changes during the event. However, regardless of the type of collision, the principle of momentum conservation applies as long as no external forces are acting on the system.
Collisions are broadly classified into:
- **Elastic Collisions**: Here, both momentum and kinetic energy are conserved. The objects bounce off each other without losing any kinetic energy during the collision.
- **Inelastic Collisions**: In these collisions, momentum is conserved, but kinetic energy is not. A common example is when colliding cars crumple together, converting some of the kinetic energy into sound, heat, or deformation energy.
- **Perfectly Inelastic Collisions**: This is an extreme case of an inelastic collision where the two objects stick together after impact, moving as a single object after the collision, sharing a common velocity.
In the exercise given, the objects experience a perfectly inelastic collision, where both objects stick together after colliding.