Physics · JEE | MECHANICAL PROPERTIES OF FLUIDS

Stokes' law gives the viscous drag force \( F \) acting on a spherical body of radius \( a \) moving with velocity \( v \) through a fluid of viscosity \( \eta \). The correct expression is:

1. A
   \( F = 4\pi\eta a v \)
2. B
   \( F = \frac{4}{3}\pi\eta a v \)
3. C
   \( F = 6\pi\eta a v \)
4. D
   \( F = 2\pi\eta a v^2 \)