Question

An engine pumps up $100kg$ of water through a height of $10m$ in $5s$. Given that the efficiency of the engine is $60\%$, what is the power of the engine? Take $g=10m{s}^{-2}$

• A. $33kW$
• B. $3.3kW$
• C. $0.33kW$
• D. $0.033kW$

Answer 1

The correct option is B $3.3kW$

Given,

$Weight=100kg$

$height=10m$

$t=5s$

$effeciency=60\%$

$g=10m/s^2$

So the output power is

$\frac{mgh}{t}=\frac{100kg\times 10m/s^2\times 10}{5}=2kw$

Now,

The Effeciency$=\frac{output-power}{input-power}\times 100\Rightarrow 60=\frac{2}{input}\times 100\Rightarrow =Input=3.33kw$