JEE Main 2019PhysicsRotational MotionMediumMCQ

JEE Main 2019 — Rotational Motion Question with Solution

JEE Main 2019 (10 Apr Shift 2)

Question

A metal coin of mass 5 g and radius 1 cm is fixed to a thin stick AB of negligible mass as shown in the figure. The system is initially at rest. The constant torque, that will make the system rotate about AB at 25 rotations per second in  5 s , is close to:

Choose an option

Show full solutionCorrect option: B
Correct answer
B2.0×10-5 N m

Step-by-step explanation

As torque τ is constant.
ω=τIt
τ=ωIt=2πn×54mr2t
= 2π×25×54×5×10-3×1×10-225
=196×10-7
≈2⋅0×10-5 N m

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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.