Units of Measurement/Pressure
Pressure is the force per unit area applied in the direction perpendicular to a surface. Mathematically, pressure is defined as
where:
- P is pressure
- F is the component of force perpendicular to the surface
- A is the area of the surface
When a force is constant over an area, the pressure acting on that area is simply
It can be given the units of N.m-2. Pressure is a scalar quantity, thus it acts in all directions at any given point. In order for pressure to create a force, the pressure must be integrated over some area.
pascal | bar | standard atmosphere | torr | pound per square inch | |
---|---|---|---|---|---|
Pa | bar | atm | Torr | psi | |
1 Pa | ≡ 1 N/m2 | 10−5 | 9.8692×10−6 | 7.5006×10−3 | 145.04×10−6 |
1 bar | 105 | ≡ 105 Pa | 0.98692 | 750.06 | 14.5037744 |
1 at | 0.980665 ×105 | 0.980665 | 0.96784 | 735.56 | 14.223 |
1 atm | 1.01325 ×105 | 1.01325 | ≡ p0 | 760 | 14.696 |
1 Torr | 133.322 | 1.3332×10−3 | 1.3158×10−3 | ≈ 1 mmHg | 19.337×10−3 |
1 psi | 6.895×103 | 68.948×10−3 | 68.046×10−3 | 51.715 | ≡ 1 lbf/in2 |