A commercial advertisement shows a pearl falling in a bottle of shampoo. If the diameter \(D\) of the pearl is quite small and the shampoo sufficiently viscous, the drag \(\mathscr{D}\) on the pearl is given by Stokes's law,

\[ \mathscr{D}=3 \pi \mu V D \]

where \(V\) is the speed of the pearl and \(\mu\) is the fluid viscosity. Show that the term on the right side of Stokes's law has units of force.