MHT CET · Physics · Rotational Motion
A disc of mass 25 kg and radius 0.2 m is rotating at 240 r.p.m. A retarding torque brings it to rest in 20 second. If the torque is due to a force applied tangentially on the rim of the disc then the magnitude of the force is
- A \(\frac{\pi}{2} \mathrm{~N}\)
- B \(2 \pi \mathrm{~N}\)
- C \(\pi \mathrm{N}\)
- D \(4 \pi \mathrm{~N}\)
Answer & Solution
Correct Answer
(C) \(\pi \mathrm{N}\)
Step-by-step Solution
Detailed explanation
\(\omega_0 = 240 \cdot \frac{2\pi}{60} = 8\pi \text{ rad/s}\) \(|\alpha| = \frac{|\omega - \omega_0|}{t} = \frac{|0 - 8\pi|}{20} = \frac{2\pi}{5} \text{ rad/s}^2\)
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