Question

Spherical balls of radius 'r' are falling in a viscous fluid of viscosity 'η' with a velocity 'v'. The retarding viscous force acting on the spherical ball is

• A. Inversely proportional to 'r' but directly proportional to velocity 'v'
• B. Directly proportional to both radius 'r' and velocity 'v'
• C. Inversely proportional to both radius 'r' and velocity 'v'
• D. Directly proportional to 'r' but inversely proportional to 'v'

Answer 1

Answer: (B)

Directly proportional to both radius 'r' and velocity 'v'

Answer 2

$F = 6\pi\eta rv$