Question

A pump is used to pump a liquid of density ${\rho }^{\prime }$ continuously through a pipe of cross section area $A$. If liquid is flowing with speed $V$, then power of pump is:

• A. $\frac{1}{3}\rho {AV}^2$
• B. $\frac{1}{2}\rho {AV}^2$
• C. $2\rho {AV}^2$
• D. $\frac{1}{2}\rho {AV}^3$

Answer 1

The correct option is D $\frac{1}{2}\rho {AV}^3$

mass=volume$\times$ density=AVt$\times \rho$

KE=$\frac{A\rho V^{3}t}{2}$

power=KE/t=$\frac{A\rho V^3}{2}$