Q. The power of a water jet flowing through an orifice of radius $r$ with velocity $v$ is
A) Zero
B) $500\ \pi r^{2}\ v^{2}$
C) $500\ \pi r^{2}\ v^{3}$
D) $\pi r^{4}v$
Explanation
(c) Volume$= av = \pi r^{2}v$
Mass $= \ \pi r^{2}v \times 1000$ SI units
Power of water jet
$= \frac{\frac{1}{2}mv^{2}}{t} = \frac{1}{2} \times \pi r^{2}v \times 1000 \times v^{2} = 500\pi r^{2}v^{3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.