[填空题]
Energy may be stored for lkqrk)4-i (h*s 9l rcrl9ba.r ;9gzm/y,m)em md6/pvclqe5wuse during peak demand by pumping water to a high reservoir when demd9cv/ ql, mm5e;m69we rl)/.ga b ympzand is low and then releasing it to drive turbines when needed. Suppose water is pumped to a lake 135 m above the turbines at a rate of $ 1.00\times10^{ 5}kg/s$ for 10.0 h at night.
(a) How much energy (kWh) is needed to do this each night? $\times10^{9 }W\cdot\,h$
(b) If all this energy is released during a 14-h day, at 75% efficiency, what is the average power output? kW
