A moving freight car collides with an identical one that is at rest. If momentum is conserved, what happens to the second car after the collision?

Answer

There will be two different possiblites as

May be one is in rest or other move

May be both will be in motion

Expalanation

According to Conservation Law of Momentum, when the two objects collide with each other, they transferred their kinetic energy to keep their momentum before or after collisions remain constant. In the present example, one moving car collides with another car which is at rest and has the same weight. There will be two possibilities after the collision as an elastic collision or perfect inelastic collision. In the elastic collision, the one car will adopt the rest position after the collision and transfer it K. E to make the rest car at the movable position. In the perfect inelastic collision, both cars will move after the collision.