Stokes Law Definition

Learn about Stokes Law, a mathematical formula describing the behavior of spheres in viscous fluids. Discover its applications, examples, and importance in science and engineering.

What is Stokes Law?

Stokes Law, named after the Irish physicist George Gabriel Stokes, is a mathematical formula that describes the behavior of a sphere falling through a viscous fluid. It is used to predict the drag force acting on the sphere due to its motion through the fluid.

The Formula

The Stokes Law formula is:

F_d = 6πμrV

  • F_d is the drag force
  • μ is the fluid viscosity
  • r is the radius of the sphere
  • V is the velocity of the sphere

Applications of Stokes Law

Stokes Law has various applications in science and engineering. It is used in fields such as fluid dynamics, pharmacology, environmental science, and more. One common application is in determining the settling velocity of particles in a fluid.


Let’s imagine a small bead falling through a container of glycerin. Using Stokes Law, we can calculate the drag force acting on the bead and predict its motion through the fluid.

Case Study

In a study on microplastic pollution in oceans, researchers used Stokes Law to analyze the behavior of plastic particles in seawater. By understanding how these particles move through the water, scientists can better mitigate the impact of ocean pollution.

Importance of Stokes Law

Stokes Law is essential for understanding the motion of particles in fluids. By accounting for viscosity and other factors, researchers can make accurate predictions and models in various scientific disciplines.


Stokes Law provides valuable insights into the behavior of objects moving through viscous fluids. Its applications are diverse and essential in many fields of study. By understanding and utilizing Stokes Law, scientists and engineers can make significant advancements in their research and development efforts.

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