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Physics · SYSTEMS OF PARTICLES AND ROTATIONAL MOTION
हिन्दीA constant torque of \( 25\text{ N}\cdot\text{m} \) acts on a body rotating about a fixed axis with moment of inertia \( 2.5\text{ kg}\cdot\text{m}^2 \). If the body starts from rest, the work done by the torque in the first 4 seconds is:
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Correct answer · Option A
2000 J
Explanation
\( \alpha = \tau / I = 25 / 2.5 = 10\text{ rad/s}^2 \). Angular displacement in 4 s is \( \theta = \frac{1}{2}\alpha t^2 = \frac{1}{2}(10)(16) = 80\text{ rad} \). Work done \( W = \tau \theta = 25 \times 80 = 2000\text{ J} \).
