Question

The S.I unit of pressure is:
A. Pascal
B. atm
C. newton
D. None of the above

Answer 1

Hint: Pressure is termed as the force imposed on a substance in a unit area. Pressure is a derived unit. It is formed by combining fundamental SI units. SI unit is the international standard accepted all over the world. There are other types of units.

Complete step by step answer:
The force imposed on an object in the unit area is termed as pressure.
An example for this is that we feel more pain when we hold a heavy bag having a thin strap than a thick strap. This is because a thin strap means it’s having less area than the thick strap. Since pressure is inversely proportional to the area, the pressure will be more for bags having thin straps. Units are of different types like CGS, FPS, MKS, and SI system of units. SI units are of two types- fundamental and derived SI units. Fundamental SI units are second metre, kilogram, candela, ampere, kelvin, and mole. Derived units are formed by combining these fundamental SI units.
Pressure is a derived unit. SI unit of pressure is (Pascal) defined as a force of one newton per square meter. There are other units for pressure like etc.
The International System of Units is abbreviated as SI unit. It is the international standard used for representation of units.
$$\text{Pa}={\displaystyle \frac{\text{N}}{{\text{m}}^2}}={\displaystyle \frac{\text{kg}}{\text{m}\times {\text{s}}^2}}$$
$$1\text{Pa}=1\text{N}{\text{m}}^{-2}=1\text{kg}{\text{m}}^{-1}{\text{s}}^{-2}$$
Barye (Ba) is the CGS unit of pressure.
$$1\text{Ba}=0.1\text{Pa}$$
$$1\text{bar}=105\text{N}.{\text{m}}^{-2}=750.06\text{torr}=0.987\text{atm}$$

Additional information:
There are different types of derived SI units like area, volume, speed, velocity, acceleration, density where all are derived from the fundamental units

Notes:
In earlier days CGS units were universally accepted. Now it changed to SI units. There are dimensionless quantities also. These are the ratio of quantities of the same type. Thus it cancels out and becomes dimensionless.