Viscosity and Newton’s law of viscosity

The viscosity can be defined as the property of fluid which resist relative motion of its adjacent layers. It is the measure of internal fluid friction due to which there is resistance to flow, The unit of viscosity is Ns/m2. 


>The shear stress on a fluid element layer is directly proportional to the rate of strain (or) velocity gradient, the constant of proportionality being called the coefficient of viscosity. 
t a (du / dy) shear stress ( t ) = m (du / dy)