Question

Two students perform an experiment with soccer balls. They kick two soccer balls so that they collide. They measure the total momentum of the two soccer balls before and after the collision. Which statement explains why the total momentum of the soccer balls before and after the collision may not be the same?(1 point)
Responses

The soccer balls each have a different momentum after the collision than before the collision.
The soccer balls each have a different momentum after the collision than before the collision.

The system does not have any external forces.
The system does not have any external forces.

The soccer balls exert forces on each other when they collide.
The soccer balls exert forces on each other when they collide.

The system has external forces, such as friction and air resistance, acting on it.
The system has external forces, such as friction and air resistance, acting on it.

Answer 1

The system has external forces, such as friction and air resistance, acting on it.

Explanation: Momentum of a closed system is conserved only when no external forces act. Friction with the ground and air resistance apply external impulses to the balls during the collision, so the total momentum need not be the same before and after.