JEE Main 2019 — Rotational Motion Question with Solution
From: JEE Main 2019 (Online) 12th April Morning Slot
Question
A circular disc of radius b has a hole of radius a at its centre (see figure). If the mass per unit area of the disc
varies as
, then the radius of gyration of the disc about its axis passing through the centre is:
This question includes a diagram. The text above accompanies the figure.
Choose an option
Show full solutionCorrect option: C
Correct answer
C
Step-by-step explanation
dI = (dm)r2
= ( dA)r2
=
m =
= ( dA)r2
=
m =
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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.