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Units of pressure

The SI unit of pressure is the pascal $$(\text{Pa})$$ which is defined as

$$$ \Torange{\text{Pa}}= \dfrac{\Tblue{\text{N}}}{\Tred{\text{m}^{2}}} = \dfrac{\Tblue{\text{kg m/s}^{2}}}{\Tred{\text{m}^{2}}} = \dfrac{\Torange{\text{kg}}}{\Torange{\text{m s}^{2}}} $$$

It is also common to use other (non-SI) units to express pressure:

  • The atmosphere ($$1\text{ atm}=101.325 \text{ kPa}$$), which is equivalent to the standard atmospheric pressure.

  • The bar ($$1\text{ bar}=10 ^{5} \text{ Pa}$$) which is very close to the standard atmospheric pressure ($$1\text{ atm}$$).

Example Pressure (estimation)
Pressure in a vacuum $$0\text{ Pa}$$
Blood pressure of healthy adult at rest $$16\text{ kPa}$$
Atmospheric pressure $$100\text{ kPa}$$
Water pressure of a garden hose $$300\text{ kPa}$$
Pressure of the average human bite $$1.10\text{ MPa}$$