Q. An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of 2 m/s. The mass per unit length of water in the pipe is 100 kg/m. What is the power of the engine
A) $800\ W$
B) $400\ W$
C) $200\ W$
D) $100\ W$
Explanation
(a) Power $= Fv = v\left( \frac{m}{t} \right)v = v^{2}(\rho Av)$
$= \rho Av^{3} = (100)(2)^{3} = 800\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.