Q. A 10 m long iron chain of linear mass density $0.8\ kg\ m^{- 1}$ is hanging freely from a rigid support. If $g = 10\ ms^{- 2}$, then the power required to lift the chain upto the point of support in $10\ s$ is
A) 10 W
B) 20 W
C) 30 W
D) 40 W
Explanation
(d) $m = 10 \times 0.8$ kg = 8 kg, $h = 5$m
$P = \frac{mgh}{t}$
$= \frac{8 \times 10 \times 5}{10} = 40\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.