A viscous force of `1.018 xx 10^(-7)` N acting on a raindrop makes it fall through air with a terminal velocity of 1 `ms^(-1)`. If the viscosity of air is `0.018 xx 10^(-3)` PI, what is the radius of the raindrop?
Hint : Stokes' law

Explanation

To solve the problem, we will use Stokes' law, which relates the viscous force acting on a spherical object moving through a fluid to its radius, the fluid's viscosity, and the object's velocity. The formula for Stokes' law is given by:

\[ F = 6 \pi \eta r V \]

Where:
- \( F \) is the viscous force (in Newtons),
- \( \eta \) is the viscosity of the fluid (in Pascal-seconds),
- \( r \) is the radius of the spherical object (in meters),
...