Question

Please explain the unit of pressure ( atmospheric pressure)?? Thank you so much.

Answer 1

Pressure, in simple terms, is a measure of the perpendicular force acting on a surface per unit area of the surface, and the simplified equation is

`P = F/A`

The base SI units of force are

• `"N"` `= ("kg"*"m")/("s"^2)`

The base SI units of area are

• `"m"^2`

So we perform the division of the units:

`P = F/A = (("kg"*"m")/("s"^2))/("m"^2) = color(red)(ulbar(|stackrel(" ")(" ""kg"/("m"*"s"^2)" ")|)`

Or, in regular units,

`color(red)(ulbar(|stackrel(" ")(" ""N/m"^2" ")|)`

This unit is equivalent to the derived unit called the pascal:

`1` `"N/m"^2 = color(blue)(1color(white)(l)"Pa"`

Often, atmospheric pressure is measured in either bars or atmospheres, so it's useful to know the conversion factors:

`1` `"atm"` `= 1.01325` `"bar"` `= 101325` `"Pa"`

and that

`1` `"bar"` `= 10^5` `"Pa"`