Question

A pump motor is used to deliver water at a certain rate from a given pipe. To obtain twice as much water from the same pipe in the same time, power of the motor has to be increased to

• A. 16 times
• B. 4 times
• C. 8 times
• D. 2 times

Answer 1

Answer: (D)

2 times

Answer 2

$P = \frac{\text{work done}}{\text{time}} = \frac{mgh}{t}$ ∴ P ∝ m

i.e. To obtain twice water from the same pipe in the same time, the power of motor has to be increased to 2 times.