JEE Main 2020 — Rotational Motion Question with Solution
From: JEE Main 2020 (Online) 3rd September Morning Slot
Question
A person of 80 kg mass is standing on the rim
of a circular platform of mass 200 kg rotating
about its axis at 5 revolutions per minute (rpm).
The person now starts moving towards the
centre of the platform. What will be the
rotational speed (in rpm) of the platform when
the person reaches its centre _________.
Enter your answer
Show full solutionCorrect answer: 9
Correct answer
9
Step-by-step explanation
2f2 = 2f1 1.8
f2 = 5 1.8 = 9
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This is a previous-year question from JEE Main 2020, 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.