# Pressure is measured using the SI unit Pascal (Pa). What is the derived SI unit for pressure?

Jan 26, 2017

$P a = N / {m}^{2} = N \cdot {m}^{- 2}$ or Newton per square meter

#### Explanation:

The Newton can be further broken down into basic units:
$N = k g \cdot m / {s}^{2}$, meaning that a force of $1 N$ will give a mass of $1 k g$ an acceleration of $1 m / {s}^{2}$

So in basic units pressure can be summarized as:

$\frac{N}{m} ^ 2 = \frac{k g \cdot \cancel{m} / {s}^{2}}{m} ^ \cancel{2} = \frac{k g}{m \cdot {s}^{2}}$, but this is hardly done.

Since the Pascal is a very small unit, the kiloPascal ($k P a = 1000 P a$) is often used. Also in use is the unit hectoPascal ($h P a = 100 P a$), as it has the same size as the milliBar ($m B a r$), that is still widely used for (atmospheric) pressure, as $1 B a r \left(1000 m B a r\right)$ is close to $1 a t m$, an older unit for pressure.