1. Compute the change in potential energy of an 82.8-kg man when he takes an elevator from the first floor to 26th floor, if the distance between floors is 4.05 m.
2. Approximately 9.4 × 106 kg of water drops 56 m over Niagara Falls every second.
a. How much potential energy is lost every second by the falling water?
b. What would be the power output of an electric generating plant that could convert all of the water's potential energy to electrical energy?
c. If the utility company sold this energy at an industrial rate of 1.6cents per kW-hr, what would be their yearly income from this source? Give your answer in dollars.