Question

Ten litre of water per second is lifted from a well through 10 m and delivered with a velocity of $10m{s}^{-1}$. If $g=10m{s}^{-2}$, then the power of the motor is

• A. 1 kW
• B. 1.5 kW
• C. 2 kW
• D. 2.5 kW

Answer 1

The correct option is B 1.5 kW

In this case, $P=\frac{mgh+\frac{1}{2}m{v}^2}{t}$
$\Rightarrow P=\frac{m}{t}[gh+\frac{v^2}{2}]$
$\Rightarrow P=\frac{10}{1}[10\times 10+\frac{10\times 10}{2}]W=1500W$