JEE Main 2019PhysicsRotational MotionEasyMCQ

JEE Main 2019Rotational Motion Question with Solution

JEE Main 2019 (09 Apr Shift 1)

Question

A stationary horizontal disc is free to rotate about its axis. When a torque is applied on it, its kinetic energy as a function of θ, where θ is the angle by which it has rotated, is given as kθ2. If its moment of inertia is I then the angular acceleration of the disc is:

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Show full solutionCorrect option: A
Correct answer
A2kIθ

Step-by-step explanation

Kinetic Energy =kθ2
12Iω2=kθ2
ω2=2kθ2I
Differentiate both side w.r.t. θ .
2ωdωdθ=4kθI
ωdωdθ=2kθI
α=2kθI

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About this question

This is a previous-year question from JEE Main 2019, 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.