Shear stress refers to the amount of force acting per unit area on a particular fluid parallel to the surface of the fluid. Newton’s law of viscosity tells us about the relationship between the shear stress and velocity gradient of fluids.
For liquids, viscosity decreases with an increase in temperature, and for gases, viscosity increases with an increase in temperature. The viscosity of any substance depends on the temperature and the state of matter. Viscosity is divided into two types: dynamic viscosity and kinematic viscosity. In other words, it is the opposite of fluidity and its SI unit is pascal-second.
Viscosity is the ability of a fluid or solid to resist the change in its shape to force from the adjacent layer.
