Types of Pressure -TS

Types of Pressure

• essure is the force applied per unit area of an object. It is also called the per unit force on an Area. There are various types of pressure that we encounter in our daily life including atmospheric pressure, Gauge pressure, etc. Pressure is calculated by taking the ratio of the force applied to the surface area of the object.

Pressure Definition

Pressure is defined as the force applied at the right angles to the surface of an object per unit area over which that force is distributed. There are specified sensors to measure the different types of pressure.

Pressure is defined as the Force per unit area. This directly means area affects the amount of pressure applied, if the area on which the force is applied is less, the pressure is less if the area is large on which force is applied. 

The SI unit for pressure is N/m2. Also, Different types of Pressure have different units in standard form.

Pressure Formula

The formula used to calculate the applied pressure is,

• P = F/A
• P = mg/A

where,
P is the Pressure
F is the Magnitude of the Force Applied
A is the Surface Area in Contact

Unit of Pressure

The SI unit of pressure is Pascal (Pa) and is denoted by the letter ‘p’. We know that pressure is a scalar quantity and Its formula is

P = F/A

Thus, we measure pressure in general units as, kgm-1s-2.

Dimension of Pressure is, [ML-1T-2]

Example of Pressure in Real Life

• While cutting fruit or a vegetable, a sharp knife is used instead of a blunt one so that the pressure applied on the fruit is more and the fruits cut easily.
• The nails that are nailed on the wall are very pointy at the end in order to put more pressure on the wall.
• Porters put a round piece of cloth on their heads in order to increase the area and the pressure is less so that heavyweights can be applied.

Types Of Pressure

We can easily classified pressure into different categories that include,

• Absolute Pressure
• Gauge Pressure
• Differential Pressure
• Sealed Pressure or Vacuum Pressure

There are different types of Pressure, and they have different units of pressure. For instance, atm is the unit used for atmospheric pressure. Let's take a look at the different types of Pressure present,

Ambient Pressure

 It is defined as the pressure applied to an object because of its surroundings including liquid, gases, and other variables.

Atmospheric Pressure

Air is present above the sea level, the pressure exerted by the air in the atmosphere is known as atmospheric pressure. The unit used for measuring the atmospheric pressure is atm. 

The human body also has Pressure inside the body which compensates for the pressure present in the atmosphere, Therefore, the Human body does not feel it. The atmospheric pressure varies due to the fluctuation in the atmosphere. The weight of air is responsible for the atmospheric pressure, and it is essential for life on Earth.

The instrument used to measure the atmospheric pressure is called Barometer. Barometer has Mercury filled, and it is vacuumed in the rest of the space. It measures Patm as pgh. 

Patm = pgh

Where, 

• p is the density of the air
• g is the acceleration due to gravity
• h is the height of the mercury

Absolute Pressure

Absolute Pressure is the pressure with respect to Zero pressure present, that is, with respect to no pressure present in the empty, free space. No pressure is obtained in a vacuum. Absolute pressure is denoted as Pabs

Differential Pressure

Differential Pressure, as the name suggests, is the difference between the two values of pressure. The pressure obtained will be lesser than either of the pressures and the unit is the same for the differential pressure obtained.

Pd = P2 - P1

Gauge Pressure

Gauge pressure is also known as Overpressure, and it is the recently invented pressure. The differential pressure obtained from atmospheric pressure and absolute pressure is known as overpressure or gauge pressure.

Below given figure shows the particular relation among Gauge Pressure, Absolute Pressure, Atmospheric pressure,

Note: In order to measure Blood pressure, an inflatable cuff is placed on the forearm, Blood flow is detected and the corresponding pressures are measured in the mercury- filled manometer (Device used to measure pressure). The maximum blood pressure is called as Systolic Pressure. The minimum blood pressure is called as Diastolic pressure.

Vacuum Pressure

The pressure which is calculated below the atmospheric pressure is known as vacuum pressure. Hence, the negative value of the gauge pressure is the vacuum pressure.