A collision is a situation in which two (or more) objects hit each other, usually during a small amount of time. Collisions can be categorized by whether or not the kinetic energy of the system changes:
Inelastic collision: The kinetic energy of the system decreases (some kinetic energy is lost, usually transforming into heat, sound, or internal energy). When two colliding objects stick together afterward, the collision is said to be perfectly inelastic.
Super-elastic collision: The kinetic energy of the system increases (some kinetic energy is gained, usually transforming from internal potential energy).
Two bicycles initially moving toward each other get in a low-speed accident in which they bounce off each other so that each bicycle is now moving at the same speed but in the opposite direction!
How could you change the context into a different form of collision? See if you can figure how two bicycles colliding could give you all three kinds of collisions!
