Fluid Pressure – Definition, Factors, Applications

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Fluid Pressure can alternatively be stated in terms of standard atmospheric pressure, which is equal to the pressure of the atmosphere (atm). Before we go into the specifics of fluid pressure, let’s first understand what pressure is. Pressure is defined as the force applied perpendicular to an object’s surface per unit area across which the force is dispersed. The pressure gauge in relation to the ambient pressure is known as gauge pressure. Fluid pressure is measured in a variety of ways. Some of these are derived from a unit of force divided by a unit of area; for example, the SI unit of pressure, the pascal (Pa), is one newton per square meter (N/m2); similarly, the imperial and US customary system’s conventional unit of pressure is psi.

Gravity, acceleration, or forces outside a closed container are the factors that cause this pressure. Here we will answer the question, “is fluid pressure scalar or vector”. Let’s have a look at the concepts related to fluid pressure, such as its formula, definition, conditions affecting fluid pressure, etc in detail.

Download Complete Fluid Mechanics Formula Notes PDF

What is Fluid Pressure?

Fluid pressure is a measurement of the force per unit area acting on an object in a fluid or on the surface of a closed container. Furthermore, this pressure is caused by acceleration, gravity, or forces that are external to the closed container. Because the fluid has no defined structure, the pressure is applied in all directions. The device used to measure the fluid pressure is Manometer.

Define Fluid Pressure

The pressure that arises at a place within a fluid as a result of the fluid’s weight is known as Fluid Pressure. Furthermore, hydraulic systems and variations in the fluid’s velocity might cause the fluid pressure to be amplified. Consider the example of a column with fluid pressure. Furthermore, the pressure in a fluid column rises in sync with the depth. The reason for this pressure rise, most importantly, is that as one goes deeper, fluid at a lower depth must support fluid that is above it.

Conditions for the Consideration of Fluid Pressure

The pressure detected at a point in the fluid that arises owing to the fluid’s weight is known as fluid pressure. It can happen in one of two ways. When there is an open channel flow or an open condition, for example. Second, it happened in a closed or flowing state. The fluid pressure is also known as static fluid pressure or hydrostatic pressure, and it takes the depth of the fluid into account. When considering the fluid’s movement, the pressure is insignificant. This indicates that the static fluid pressure is unaffected by surface area, container shape, or liquid quantity or volume. There are two scenarios in which fluid pressure is considered:

  • In an open state or with an open channel flow
  • In a closed state or through a closed channel

Fluid Pressure Formula

The following relation can be used to calculate the pressure in fluids. The equation assumes certain properties of the fluid, such as that it is ideal and incompressible. The definition of an ideal fluid is one that has no friction and is inviscid (zero viscosity). Mathematically, the Fluid Pressure Formula is

Pfluid = P + ρgh


  • P = Pressure at the reference point
  • Pfluid = Pressure at a point taken in fluid
  • ρ = Density of the fluid
  • g = Acceleration due to gravity (considering earth g = 9.8 m/s2)
  • h = Height from the reference point

Is fluid pressure scalar or vector

Fluid pressure is a scalar quantity because the pressure exerted by the liquid is equal in all directions and does not depend on the direction.

Factors Affecting Fluid Pressure

Because the motions induce very minor changes in the pressure, pressure in open conditions may usually be approximated as the pressure in static or non-moving situations (even in the ocean where there are waves and currents). Such circumstances are consistent with fluid statics principles. Fluid pressure is influenced by the depth and density of the fluid.


At the bottom or base of the container, fluids exert more pressure or force. The weight of all the fluid above it exerts pressure at the depth. Therefore the magnitude of fluid pressure increases with its distance from the surface. The fluid pressure increases as we travel deeper. At the bottom, the fluid pressure is the highest.

Effect of Gravity on Fluid Pressure

The effect of gravity on fluid pressure is proportional to the distance from the surface of the liquid. The relation on which it depends is:

P = m * g * h

This shows that pressure is directly proportional to gravity as it depends on the h of the column.


The liquid imposes a greater pressure due to its density, whereas the gas exerts a lower pressure due to its density. The molecules in liquids are organized in a closed-packed way. As a result, a collision may occur, causing the fluid pressure to rise.

Applications of Fluid Pressure

The breathing process is likewise controlled by pressure, and it plays an important part in the respiratory system. Inhalation occurs when there are pressure differences between the lungs and the atmosphere, allowing air to enter the lungs. Fluid pressure is used in the following ways.

  • Hydraulic brakes
  • Artesian well
  • Blood pressure
  • Hydraulic head
  • Plant cell turgidity
  • Pythagorean cup
  • Pressure washing
Important Topics for Gate Exam
Induction Motor Inductors in Parallel
Kinematic Pair Kirchhoff’s Law
Laplace Transform Maximum Shear Stress Theory
Modulus of Elasticity Neutral Axis
Newtonian Fluids Newtonian Mechanics


Our Apps Playstore
SSC and Bank
Other Exams
GradeStack Learning Pvt. Ltd.Windsor IT Park, Tower - A, 2nd Floor, Sector 125, Noida, Uttar Pradesh 201303
Home Practice Test Series Premium