I know that momentum is conserved in inelastic collisions. In other words, if the kinetic energy of the system is converted to potential, the momentum is still conserved
Suppose we have the situation where a ball is rolling up a hill. The ball does not have enough energy to get to the top of the hill, and so, it rolls back down.
The initial momentum was directed towards the hill, and the final momentum is directed away from the hill. How is momentum conserved?