Question

The viscous force acting on a body falling under gravity in a viscous fluid will be

• A. $\frac{6\pi V}{\eta r}$
• B. $\frac{6\pi \eta r}{V}$
• C. $6\pi \eta rV$
• D. $\frac{rV}{6\pi \eta }$

Answer 1

Answer: (C)

$6\pi \eta rV$

According to Stokes Law, the viscous force acting on a body falling under gravity in a viscous fluid with viscosity $\eta$ is given by

$F_r=6\pi \eta rV$ where $V$ is the velocity and $r$ is the radius of the spherical body.