Q. A mass $m$ hangs with a help of a string wrapped around a pulley on a frictionless bearing. The pulley has mass 𝑚 and radius $R$. Assuming pulley to be a perfect uniform circular disc, the acceleration of the mass $m$, if the string does not slip on the pulley, is
A) $\frac{3}{2}\ g$
B) $g$
C) $\frac{2}{3}\ g$
D) $\frac{g}{3}$
Explanation
(c) [image:5_image210.emf]
$mg - T = ma$
$TR = \frac{mR^{2}\alpha}{2}$
$T = \frac{mR\alpha}{2} = \frac{ma}{2}$
$mg - \frac{ma}{2} = ma$
$\frac{3ma}{2} = mg$
$a = \frac{2g}{3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.