Question

A pump of 200 W power is lifting 2 kg water per second from an a average depth of 10 m. The velocity with which water comes out of the pump is :

$(g=9.8{ms}^{-2})$

• A. $2{ms}^{-1}$
• B. $2.5{ms}^{-1}$
• C. $44{ms}^{-1}$
• D. $10{ms}^{-1}$

Answer 1

Answer: (A)

$2{ms}^{-1}$

Given,

$m=2kg$

$h=10m$

$g=9.8m/s^2$

$P=200W$

Power, $P=\frac{Energy}{time}$

$P=\frac{mgh+\frac{1}{2}m{v}^2}{1sec}$

$200=mgh+\frac{1}{2}m{v}^2$

$200=2\times 9.8\times 10+\frac{1}{2}\times 2v^2$

$200=196+v^2$

$v^2=4$

$v=\sqrt{4}m/s$

$v=2m/s$

The correct option is A.