Q. A mass $M$ is lowered with the help of a string by a distance $h$ at a constant acceleration $g/2$. The work done by the string will be
A) $\frac{Mgh}{2}$
B) $\frac{- Mgh}{2}$
C) $\frac{3Mgh}{2}$
D) $\frac{- 3Mgh}{2}$
Explanation
(b) Tension in the string
$T = M(g - a) = M\left( g - \frac{g}{2} \right) = \frac{Mg}{2}$
$W = \ Force\ \times \ displacement$
$= - \frac{Mgh}{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.