In an incompressible static fluid column, the rate of increase of pressure in the vertical direction is equal to weight density of fluid at that point. Which of the following is the law for this statement?

Concept:

Hydrostatic Law:

The pressure at any point in a fluid at rest is obtained by the Hydrostatic Law which states that In an incompressible static fluid column, the rate of increase of pressure in a vertically downward direction must be equal to the specific weight of the fluid at that point.​​

P = ρgh

where P = pressure above atmospheric pressure and h = height of the point from the free surface.

Important Points

Pascal’s principle: 

• Pascal’s Law is the principle of transmission of fluid pressure.
• It says that "a pressure exerted anywhere in a point of the confined fluid is transmitted equally in all directions throughout the fluid”.

Newton’s law of viscosity:

The shear stress is directly proportional to the rate of shear strain or the rate of angular deformation of a fluid particle. The fluid-particle tends to deform continuously when it is in motion.

where, τ = shear stress, μ = dynamic viscosity, du/dy = shear strain rate

From the above equation, we can say that Newton’s law of viscosity is a relationship between shear stress and the rate of shear strain.