In any elastic head-on collision, the relative speed of the two objects after the collision has the same magnitude (but opposite direction) as before the collision, no matter what the masses are.

Question

Quizplus · Accepted Answer

In an elastic head-on collision, both momentum and kinetic energy are conserved, leading to the relative speed of the two objects being the same before and after the collision, just in opposite directions.

In Any Elastic Head-On Collision, the Relative Speed of the Two