Question

Your friend says that the Law of Conservation of Momentum is violated when a ball rolls down a hill at an increasing speed. You reply:

a) The momentum of the ball is really being conserved
b) Your friend is right because the momentum of the ball is not being conserved
c) Your friend is wrong because the net external force on the ball is not zero and
so the Law of Conservation of Momentum does not apply to this example
d) None of the above