Newton's Law of Viscosity

\[\tau = \frac{F}{A}=\mu \frac{U}{Y}\]

\(\tau\) = shear stress
\(F\) = force applied to the top plate
\(A\) = surface area of top plate
\(\mu\) = viscosity of fluid

\[\tau = \mu \frac{dv}{dy}\] Newton’s law of viscosity and states that the shear stress between adjacent fluid layers is proportional to the negative value of the velocity gradient between the two layers.