Question

A pump motor is used to deliver water at a certain rate from a given pipe to a certain height. 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

The correct option is

C

$P^{\prime }=\frac{E}{t}$

$P^{\prime }=\frac{\frac{1}{2}m{v}^2}{t}$

$P^{\prime }=\frac{\left(\frac{1}{2}2m{\left(2v\right)}^2\right)}{t}$

$P^{\prime }=8P$