Inelastic collisions

[A-Train]

Why is Kinetic Energy lost in an inelastic collision but not in an elastic collision?

[HallsofIvy]

Uhh, because that's the definition of "inelastic" collision?

If you are looking for more- like what makes on collision elastic and another inelastic, please rephrase the question.

(If you wondering what happens to the energy, typically it becomes heat energy in the colliding bodies.