Chapter 2.3, Problem 29P

(a)

To determine

The limiting velocity of a solid sphere of radius $a$ and density $\rho$ falling freely in a medium of density $\rho \text{'}$ and the co-efficient of viscosity $\mu$ where a body falling in a relatively dense fluid, is acted on by three forces; a resistive force $R$, a buoyant force $B$, and its weight $w$ due to gravity.

(b)

To determine

An expression for $e$, such that $E$ has been adjusted, so the droplet is stationary where a field of strength $E$ exerts a force $Ee$ on a droplet with charge $e$