Water is pumped from a lake to a storage tank 20 m above at a rate of 70 L/s while consuming 20.4 kW of electric power. Disregarding any frictional losses in the pipes and any changes in kinetic energy, determine a) the overall efficiency of the pump-motor unit, b) the pressure difference between the inlet and the outlet of the pump, and c) if the diameter of the pipe is 9 cm, determine at 10 m above the lake the change in each component (i.e. kinetic energy, etc) of the mechanical energy with respect to their values at the outlet of the pump.