Approximately $5.5 \times 10^{6} \mathrm{~kg}$ of water falls $50 \mathrm{~m}$ over Niagara Falls each second. (a) What is the decrease in the gravitational potential energy of the water-Earth system each second? (b) If all this energy could be converted to electrical energy (it cannot be), at what rate would electrical energy be supplied? (The mass of $1 \mathrm{~m}^{3}$ of water is $\left.1000 \mathrm{~kg} .\right)(\mathrm{c})$ If the electrical energy were sold at 1 cent $/ \mathrm{kW} \cdot \mathrm{h}$, what would be the yearly income?