JEE Main 2020 — Rotational Motion Question with Solution
From: JEE Main 2020 (Online) 7th January Evening Slot
Question
Mass per unit area of a circular disc of radius depends on the distance r from its centre as = A + Br
. The moment of inertia of the disc about the axis, perpendicular to the plane and
assing through its centre is:
Choose an option
Show full solutionCorrect option: A
Correct answer
A
Step-by-step explanation
dI = dm(r2)
and dm = 2rdr
dI = 2rdr(r2) = 2r3dr
Given = A + Br
dI = 2(A + Br)r3dr
I =
=
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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.