Uses
The pascal (Pa) or kilopascal (kPa) as a unit of pressure measurement is widely used throughout the world and has largely replaced the pounds per square inch (psi) unit, except in some countries that still use the Imperial measurement system.
Tectonophysicists use the gigapascal (GPa) in measuring or calculating tectonic forces within the earth.
In materials science, megapascals (MPa = N/mm2) or gigapascals (GPa = kN/mm2) are commonly used to measure stiffness or tensile strength of materials. Examples of (approximate) tensile modulus for several common substances include nylon at 2-4; hemp (fibre) at 58, aluminium at 69; tooth enamel at 83, copper at 117, steel at approximately 200 GPa, silkworm silk at 500, and diamond at 1220.
The pascal is also equivalent to the SI unit of energy density, J/m3. This applies not only to the thermodynamics of pressurized gasses, but also to the energy density of electric, magnetic, and gravitational fields.
Other, older units of measure occasionally used for pressure are millimeters of mercury (Torr) and millimetres of water (1.0 mmH2O = 9.80665 Pa).
In the cgs system, the unit of pressure is the barye (symbol ba), which is equal to one decipascal. The older kilogram-force per square centimetre corresponds to 98.0665 kPa, but is it often rounded off to 100 kPa in practice.
In the former mts system, the unit of pressure is the pièze (symbol pz), which is equal to one kilopascal.
Airtightness testing of buildings is measured at 50 Pa or 0.2 inches of water.
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