JEE Main 2025 — Rotational Motion Question with Solution
JEE Main 2025 (23 Jan Shift 2)
Question
A circular disk of radius R meter and mass M kg is rotating around the axis perpendicular to the disk. An external torque is applied to the disk such that , where is the angular position of the rotating disc as a function of time .
How much power is delivered by the applied torque, when ?
Choose an option
Show full solutionCorrect option: D
Correct answer
D
Step-by-step explanation
$\begin{aligned}
& \theta=5 \mathrm{t}^2-8 \mathrm{t} \\
& \omega=\frac{\mathrm{d} \theta}{\mathrm{dt}}=10 \mathrm{t}-8 \\
& \alpha=\frac{\mathrm{d} \omega}{\mathrm{dt}}=10 \\
& \therefore \mathrm{p}=\tau \omega \\
& =(\mathrm{I} \alpha) \omega \\
& =\left(\frac{\mathrm{mR}^2}{2}\right) \alpha \omega \\
& =\left(\frac{\mathrm{mR}^2}{2}\right)(10)(10
\end{aligned}$
Put
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This is a previous-year question from JEE Main 2025, covering the Rotational Motion chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.