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Question: Answered & Verified by Expert
If a disc of mass $M$ and radius $R$ rotates with an angular acceleration $a_{\text {, }}$ of the torque acting on the disc is
PhysicsRotational MotionTS EAMCETTS EAMCET 2018 (07 May Shift 1)
Options:
  • A $M R^2 a$
  • B $\frac{M R^2 a}{2}$
  • C $\frac{2 M R^2 a}{5}$
  • D $\frac{M R^2 a}{12}$
Solution:
2803 Upvotes Verified Answer
The correct answer is: $\frac{M R^2 a}{2}$
$\therefore$ Moment of inertia of disc, $Y=\frac{1}{2} M R^2$
Angular acceleration, $\alpha=a$ (given)
So, torque $\tau=Y \alpha$,
$$
\tau=\left(\frac{1}{2} M R^2\right)\langle a\rangle \Rightarrow \tau=\frac{M R^2 a}{2}
$$

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