JEE Main 2023PhysicsMechanical Properties of FluidsHardMCQ

JEE Main 2023 — Mechanical Properties of Fluids Question with Solution

JEE Main 2023 (06 Apr Shift 1)

Question

A small ball of mass M and density ρ is dropped in a viscous liquid of density ρ0. After some time, the ball falls with a constant velocity. What is the viscous force on the ball?

Choose an option

Show full solutionCorrect option: C
Correct answer
CF=Mg1-ρ0ρ

Step-by-step explanation

The buoyant force is given by 

B=Vρ0g

where V is the volume of the ball. The weight of the ball

W=Mg=Vρg, is acting in the opposite direction of the buoyant force . Hence, at terminal velocity

Mg-B=Fv

⇒B+Fv=Mg

⇒Fv=Vρg-Vρ0g⇒Fv=ρVg(1-ρ0ρ)⇒Fv=Mg(1-ρ0ρ)

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About this question

This is a previous-year question from JEE Main 2023, 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.