JEE Main 2021PhysicsMechanical Properties of FluidsHardMCQ

JEE Main 2021 — Mechanical Properties of Fluids Question with Solution

JEE Main 2021 (26 Feb Shift 1)

Question

A large number of water drops, each of radius r, combine to have a drop of radius R. If the surface tension is T and mechanical equivalent of heat is J, the rise in heat energy per unit volume will be:

Choose an option

Show full solutionCorrect option: D
Correct answer
D3T J1r-1R

Step-by-step explanation

n×43πr3=43πR3

∴ n1/3r=R

∴ Total change in surface energy

=n4πr2-4πR2T

⇒4πTnr2-R2

∴ Heat energy

=4πTnr2-R2J×43πR3=3 T Jnr2R3-1R

Put nr3=R3

∴ 3TJ1r-1R

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About this question

This is a previous-year question from JEE Main 2021, covering the Mechanical Properties of Fluids 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.