Question

question 3 of 28 a 1200 kg car travelling 3.0 m/s to the north runs into a telephone pole. the telephone pole completely stops the car. which of the following is true? a momentum is not conserved because outside forces act on the system. b the total momentum before the collision equals the total momentum after the collision. c the momentum of the telephone pole after the collision is 3600 kg m/s to the south. d the momentum of the telephone pole after the collision is 3600 kg m/s to the north.

Explanation:

Momentum conservation requires no external forces. The telephone pole, fixed to the ground, experiences external forces from the Earth during collision, so system momentum is not conserved. The car stops, and the pole doesn't move, so total momentum before (3600 kg·m/s north) ≠ after (0). Pole momentum remains 0.

Answer:

A. Momentum is not conserved because outside forces act on the system.