Question

Why is Stoke's law applicable at low Reynolds number but not at high Reynolds numbers?

Answer 1

Stokes's law is applicable at low Reynold's number because it is derived from Navier Stokes's law with assumptions that in the flow viscous force dominates and tiny particles follow the streamline of such creeping flow flow but when the flow because turbulent at high Reynold's number then flow becomes chaotic and in that case inertial force starts dominating an particles moves in random motion and so we cannot apply Stoke's law to such flow.