Verified Solution • 2025–26 Session moderate

QJEEM22Ph7be8: JEE Main 2022 Physics - Class 11 JEEM22Ph7be8 Solution: A water drop of radius 1 m falls in a situation where the…

A water drop of radius 1 μ\mu m falls in a situation where the effect of buoyant force is negligible. Co-efficient of viscosity of air is 1.8 ×\times 10 −- 5 Nsm −- 2 and its density is negligible as compared to that of water 106 gm −- 3. Terminal velocity of the water drop is :

(Take acceleration due to gravity = 10 ms −- 2)

Multiple Choice Options

  • A 145.4 ×\times 10 −- 6 ms −- 1
  • B 118.0 ×\times 10 −- 6 ms −- 1
  • C 132.6 ×\times 10 −- 6 ms −- 1
  • D 123.4 ×\times 10 −- 6 ms −- 1

Step-by-Step Verified Solution

6πηrv=mg6\pi \eta rv = mg

6πηrv=43πr3ρg6\pi \eta rv = {4 \over 3}\pi {r^3}\rho g

or v=29ρr2gη=29×103×(10−6)2×101.8×10−5v = {2 \over 9}{{\rho {r^2}g} \over \eta } = {2 \over 9} \times {{{{10}^3} \times {{({{10}^{ - 6}})}^2} \times 10} \over {1.8 \times {{10}^{ - 5}}}}

=123.4×10−6= 123.4 \times {10^{ - 6}} m/s

Related Learning Resources & Exam Preparation

JEE Main PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring