[填空题]
Water flows over a dam at the raoz) o *.lew3tcpx k q5qzw-1-kte of 650kg/s and falls u0; kowa;w3/mph3 0- ol ludhwvertically 81 m before striking;w/u0wko 3; 0ah3l mp lo-dhwu the turbine blades. Calculate
(a) the speed of the water just before striking the turbine blades (neglect air resistance), $\approx$ m/s
(b) the rate at which mechanical energy is transferred to the turbine blades, assuming 58% efficiency. W
