Water Flows Over a Waterfall That Is 20 M $4.0 \times 10 ^ { 4 } \mathrm {~kg} / \mathrm { s }$

Short Answer

Water flows over a waterfall that is 20 m high at the rate of $4.0 \times 10 ^ { 4 } \mathrm {~kg} / \mathrm { s }$
If this water powers an electric generator with a 40% efficiency, how many watts of electric power can be supplied?