Let’s go through the following subtopics: (1) Pressure definition (2) formula of pressure and (3) SI unit of pressure

## Definition of Pressure

**Pressure (P) is defined as the normal force F per unit area A over which the force is applied, or P = F/A **…………… (1)**To define the pressure at a specific point, the pressure is defined as the force dF exerted by a fluid over an infinitesimal element of area dA containing the point, i.e., P = dF/dA ………….(2)**

## Formula of Pressure

**P = F/A **…………… (1) **P = dF/dA ………….(2**)

## Importance of surface area to calculate pressure

*You must have noticed that a sharp needle is able to poke through the *skin when a small force is exerted, but applying the same force with a finger does not puncture the skin. While injecting vaccines* this is what we notice always.***A given force can have a significantly different effect, depending on the area over which the force is exerted.**

For instance, a force applied to an area of 1 mm^2 has a pressure that is 100 times as great as the same force applied to an area of 1 cm^2.

## SI unit of Pressure: Pascal

Note that although the force is a vector, pressure is a scalar. Pressure is a scalar quantity because it is defined to be proportional to the magnitude of the** force acting perpendicular to the surface area**.

The SI unit for pressure is the pascal (Pa), named after the French mathematician and physicist Blaise Pascal (1623–1662), where**1 Pa = 1 N/m^2.**