Question

The power of an engine which draws 1000 kg of water from a well of depth 9 m in one minute is (acceleration due to gravity $g = 10$ m/s$^2$)

• A. 1.5 kW
• B. 1.5 W
• C. 150 W
• D. 15 kW

Hint:

To compute power, divide the total work done (mgh) by time in seconds.

Answer 1

The Correct Option is A

Work done to lift water = $mgh = 1000 \times 10 \times 9 = 90000$ J
Time taken = 1 minute = 60 s
Power = $\dfrac{\text{Work}}{\text{Time}} = \dfrac{90000}{60} = 1500$ W = 1.5 kW