Q. A pulley fixed to the ceiling carries a string with blocks of masses $m$ and 3$m$ attached to its ends. The masses of string and pulley are negligible. When the system is released, the acceleration of center of mass will be
A) Zero
B) $- \frac{g}{4}$
C) $\frac{g}{2}$
D) $- \frac{g}{2}$
Explanation
(c) Let $T$ be the tension in the string carrying
The masses $m\ and\ 3m$
Let $a$ be the acceleration, then
$T - mg = ma$ …(i)
$3mg - T = 3ma$ …(ii)
Adding Eqs. (i) and (ii), we het
$2mg + 4ma$
$\Longrightarrow$ $a = \frac{g}{2}$
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Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.