Water falls over a dam of height $h$ with a mass flow rate of $I_{V}$ in units of kilograms per second.
(a) Show that the power available from the water is $$P=I_{v} g h$$ where $g$ is the free-fall acceleration.
(b) Each hydroelectric unit at the Grand Coulee Dam takes in water at a rate of $8.50 \times 10^{5} \mathrm{~kg} / \mathrm{s}$ from a height of $87.0 \mathrm{~m} .$ The power developed by the falling water is converted to electric power with an efficiency of $85.0 \% .$ How much electric power does each hydroelectric unit produce?