Postby **twistor** » Mon Apr 23, 2007 11:58 am

1) Power = energy / time. So how much energy is dissipated by this waterfall in 1 sec? You know that after 1 second 1.20 kg of water have fallen over the hill. What energy does that correspond to?

2) In any conservative system (i.e. a gravitational field) the sum of kinetic and potential energies is constant. So how much energy does it have before it strikes?. After the ball stops it has no more kinetic energy. I would suggest drawing a picture where you clearly indicate that at the top of the well the ball has 0 potential energy. Hint: The potential energy should be negative when the ball is in the well.