Water flows (v 0) over a dam at the rate of 650 kg/s and falls vertically 81m

Question:

Water flows (v ≈ 0) over a dam at the rate of 650 kg/s and falls vertically 81m before striking the turbine blades. Calculate. (br) (a) The speed of the water just before striking the turbine blades (neglect air resistance), and. (br) (b) The rate at which mechanical energy is transferred to the turbine blades, assuming 58% efficiency.(br)