What is the derivation of Stokes' Law and how does it relate to the motion of small particles in a fluid?

Stokes' Law, derived by Sir George Stokes in the 19th century, describes the drag force experienced by small particles moving through a fluid. It states that the drag force is directly proportional to the particle's velocity and size, as well as the viscosity of the fluid. This law is important in understanding the motion of small particles in a fluid, such as how they settle or move in response to external forces like gravity or fluid flow.