Question

A pump is required to lift $1000\text{kg}$ of water per minute from a well $20\text{m}$ deep and eject it at a rate of $20{\text{ms}}^{-1}.$ What HP (horsepower) engine is required for the purpose of lifting water?

• A. $7.85$
• B. $8.93$
• C. $1.7$
• D. $2.6$

Answer 1

The correct option is B $8.93$

We know that the power,$P=\frac{W}{\Delta t}=\frac{mgh+\frac{1}{2}m{v}^2}{t}$

$($as $t=1\text{min})$

$=\frac{(1000\times 10\times 20)+\frac{1}{2}\times 1000\times (20{)}^2}{60}$
$=6666.66W$

Converting to horse power
$=6666.66W=\frac{6666.66}{746}=8.93hp$
Hence option B is the correct answer