JEE Main 2023PhysicsRotational MotionHardNumerical

JEE Main 2023 — Rotational Motion Question with Solution

JEE Main 2023 (11 Apr Shift 2)

Question

A circular plate is rotating in horizontal plane, about an axis passing through its centre and perpendicular to the plate, with an angular velocity ω. A person sits at the centre having two dumbbells in his hands. When he stretched out his hands, the moment of inertia of the system becomes triple. If E be the initial Kinetic energy of the system, then final Kinetic energy will be Ex. The value of x is

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Show full solutionCorrect answer: 3
Correct answer
3

Step-by-step explanation

The kinetic energy is given by 

E=12Iω2=L22I

It is given that the new moment of inertia

 I'=3I 

Clearly, the final kinetic energy is

Ef=L22I'=L26I⇒Ef=E3

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About this question

This is a previous-year question from JEE Main 2023, 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.