A pump must do of work to raise water to a storage tank

PHYSICS · Subjective · A Level · Physics · Mechanics and materials · Mechanics and materials

Problem

A pump must do

1.5\times10^{6}\,\text{J}

of work to raise water to a storage tank. It runs at

500\,\text{W}

for the first

2.0\,\text{min}

, after which its output drops and remains steady at

300\,\text{W}

. Calculate the additional time, in minutes, the pump must operate at the reduced power to finish the required work.