Question

A moving bumper car hits the back bumper of a stationary bumper car. The momentum of the stationary car increases. Which happens to the momentum of the moving bumper car?
a. it stays the same
b. it decreases
c. it is converted to inertia

Answer 1

consider newton's third law

with every action, there is an equal and opposite reaction.

which means when it pushes against the stationary car, an equal force pushes back

Answer 2

there is no any external force so momentum conservation is apply which say initial momentum = final momentum. Now initial momentum of stationary car is zero but final momentum is not 0 this momentum come from moving car so final momentum of moving car is decreases.