JEE Main 2015PhysicsMechanical Properties of SolidsHardMCQ

JEE Main 2015 — Mechanical Properties of Solids Question with Solution

JEE Main 2015 (04 Apr)

Question

A pendulum made of a uniform wire of cross sectional area A has time period T. When an additional mass M is added to its bob, the time period changes to TM . If the Young's modulus of the material of the wire is Y, then 1Y is equal to:
(g=gravitational acceleration)

Choose an option

Show full solutionCorrect option: B
Correct answer
B T M T 2 - 1 A⁡ Mg⁡

Step-by-step explanation


Initial length =l. Time period T=2πlg        ...(i). After suspending mass M,. Youngs modulus Y=StressStrain=FA∆ll=Fl∆l A

Change in length of wire Δl=FlAY

Now time period TM=2πl+Δlg  ...(ii)       

TTM=2πlg2πl+Δlg        ∵ i ii

T2TM2=ll+Δl

⇒Tm2T2=1+∆ll
1+FAY=TmT2putting value of ∆l
1Y=TmT2-1AF
F=Mg
1Y=TmT2-1AMg

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About this question

This is a previous-year question from JEE Main 2015, covering the Mechanical Properties of Solids 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.