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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 or the US customary system, including the United States.
Pressure as a function of the height above the sea level. There are two equations for computing pressure as a function of height. The first equation is applicable to the atmospheric layers in which the temperature is assumed to vary with altitude at a non null lapse rate of : = [,, ()] ′, The second equation is applicable to the atmospheric layers in which the temperature is assumed not to ...
The ground pressure of motorized vehicles is often compared with the ground pressure of a human foot, which can be 60 – 80 kPa while walking or as much as 13 MPa for a person in spike heels. [3] Increasing the size of the contact area on the ground (the footprint) in relation to the weight decreases the unit ground pressure.
In SI units, the unit is converted to the SI derived unit pascal (Pa), which is defined as one newton per square metre (N/m 2). A newton is equal to 1 kg⋅m/s 2, and a kilogram-force is 9.80665 N, [3] meaning that 1 kgf/cm 2 equals 98.0665 kilopascals (kPa).
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth.The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, [1] 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. [2]
If we had a column of mercury 767 mm high, we could calculate the atmospheric pressure as (767 mm)•(133 kN/m 3) = 102 kPa. See the torr , millimeter of mercury , and pascal (unit) articles for barometric pressure measurements at standard conditions.
Until 1982, STP was defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 101.325 kPa (1 atm). Since 1982, STP is defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 100 kPa (1 bar). Conversions between each volume flow metric are calculated using the following formulas: Prior to 1982,
1–10 kPa Typical explosion peak overpressure needed to break glass windows (approximate) [40] 2 kPa Pressure of popping popcorn (very approximate) [41] [42] 2.6 kPa 0.38 psi Pressure at which water boils at room temperature (22 °C) (20 mmHg) [43] 5 kPa 0.8 psi Blood pressure fluctuation (40 mmHg) between heartbeats for a typical healthy ...