Question

The power of a motor pump in a house is $\text{20 W}$. How much water per minute can the pump raise to a height of $\text{10 m}$?
Take acceleration due to gravity $g=10m{s}^{-2}$

• A. 6 kg
• B. 20 kg
• C. 12 kg
• D. 24 kg

Answer 1

The correct option is C

12 kg

Work done $=mgh,$ where $m$ is the mass, $g$ is the acceleration due to gravity and $h$ is the height.
Given time = 1 minute = 60 seconds
height $h=10m$
$\text{Power}=\frac{\text{Work done}}{\text{Time taken}}$
$\text{Power}=\frac{\text{mgh}}{\text{Time taken}}$
So, 20 = $\frac{m\times 10\times 10}{60}$
$\Rightarrow m=12kg$
Therefore, the pump can raise water of mass 12 kg in one minute.