# Test and Measurement World

## Test and Measurement World Terminology Section

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## Static Pressure Vs Dynamic Pressure | Difference between Static Pressure and Dynamic Pressure

This page compares Static Pressure vs Dynamic Pressure and mentions difference between Static Pressure and Dynamic Pressure.

Pressure of the fluid contained in container is defined as force per unit area exerted by fluid on the container wall.

### Static Pressure

Definition:
When the fluid is in equilibrium, the pressure at a point is identical in all the directions and it is independent of orientation. This is known as static pressure. Here static refers to "still or standing".

➨It can be expressed as ratio of force to surface area. (Static Pressure = F/A)
➨It is calculated in units of PSI (Relative to Atmosphere) or MPa (Megapascal, relative to Vacuum).

### Dynamic Pressure

Definition:
When pressure gradient occur within a continuum of pressure, the attempt to restore equilibrium results in fluid flow from regions of high pressure to regions of low pressure. In this case, pressures are no longer independent of directions and are known as dynamic pressure. Here dynamic refers to "moving".

Example: Fluid moving in a piece of pipe is known as dynamic pressure. Fluid can be water or steam etc. It is also called moving pressure.

➨Dynamic pressure is much like the kinetic energy. It is kinetic energy per unit volume of a fluid particle.
➨It is calculated as per following equation.
Dynamic Pressure = (ρ/2 )* V2,
Where ρ = Density of liquid in kg/m3
V = Speed with which fluid is moving in m/s

The unit of dynamic pressue is Pascals.