Question

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 D on the pearl is given by Stokes's law, D=3πμVD where V is the speed of the pearl and μ is the fluid viscosity. Show that the term on the right side of Stokes's law has units of force.

Answer 1

Given that

D=3πμVD

We know that

Unit of μ is N.s/m²

Unit of V is m/s

Unit of D is m.

3 and π are scalar .

3πμVD = (N.s/m²) x (m/s) x m= N

So we can say that right side have unit or force.