At low Reynolds number the inertial terms in the Navier-Stokes equation are relatively unimportant; the flow pattern is determined by a balance of the viscous forces and the pressure gradients in the fluid. As a consequence, expressions for the velocity, drag forces, and the like do not involve the fluid density directly. One of the nice features of flow at low Reynolds numbers is that the flow is laminar--the viscosity quickly damps out any turbulent effects. We'll consider two simple low Reynolds number flows, both of which have practical applications.