An oil pump is being driven by the shaft of an electric motor. The motor consumes 44 kW of power while pumping the oil – having a density of 0.860 g/cm3 – at a rate of 0.1 m3/s. The inlet and outlet diameters of the pipe are 8 cm and 12 cm, respectively. If the pressure rise of the oil in the pump is measured to be 500 kPa, and the electric motor efficiency is 90%, determine the mechanical efficiency of the pump.