Question

Water is pumped from a depth of 10 m and delivered through a pipe of cross-section ${10}^{-2}{m}^2$. If it is needed to deliver a volume of ${10}^{-1}{m}^3$ per second, the power required will be:

• A. 4.9 KW
• B. 9.8 KW
• C. 15 KW
• D. 10 KW

Answer 1

Answer: (B)

. 9.8 kW.

Given,

Height = $h=10m$

Volume delivered per second = $\frac{V}{t}={10}^{-1}{m}^3/s$

We know that,

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

Since work done = $W=mgh$

$\therefore P=\frac{mgh}{t}$

$P=\frac{V\rho gh}{t}$

Since mass = $m=V\rho$

$P={10}^{-1}\times {10}^3\times 9.8\times 10$

$P=9.8kW$.