Two objects collide and bounce apart. Assuming no outside forces act on the system, which best describes the total momentum after the collision?

Question

It is always greater than it was before the collision.
It is often greater than it was before the collision.
It is always the same as it was before the collision.
It is often the same as it was before the collision.

Answer 1

The best description of the total momentum after the collision, assuming no outside forces act on the system, is:

It is always the same as it was before the collision.

This principle is known as the conservation of momentum, which states that the total momentum of a closed system remains constant if no external forces are acting on it.