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On average, a column of air with a cross-sectional area of 1 square centimetre (cm 2), measured from the mean (average) sea level to the top of Earth's atmosphere, has a mass of about 1.03 kilogram and exerts a force or "weight" of about 10.1 newtons, resulting in a pressure of 10.1 N/cm 2 or 101 kN/m 2 (101 kilopascals, kPa).
The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m 2). [1] It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar , and the kilopascal (1 kPa = 1000 Pa), which is equal to ...
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). In some older publications, kilogram-force per square centimetre is abbreviated ksc ...
10 kPa 1.5 psi Pressure increase per meter of a water column [26] 10 kPa 1.5 psi Decrease in air pressure when going from Earth sea level to 1000 m elevation [citation needed] +13 kPa +1.9 psi High air pressure for human lung, measured for trumpet player making staccato high notes [48] < +16 kPa +2.3 psi
At 20 °C and 101.325 kPa, dry air has a density of 1.2041 kg/m 3. At 70 °F and 14.696 psi , dry air has a density of 0.074887 lb / ft 3 . The following table illustrates the air density–temperature relationship at 1 atm or 101.325 kPa: [ citation needed ]
In fact the specific weight of water is 9.8 kN/m 3 and the specific weight of mercury is 133 kN/m 3. So, for any particular measurement of pressure head, the height of a column of water will be about [133/9.8 = 13.6] 13.6 times taller than a column of mercury would be.
The standard atmosphere was originally defined as the pressure exerted by a 760 mm column of mercury at 0 °C (32 °F) and standard gravity (g n = 9.806 65 m/s 2). [2] It was used as a reference condition for physical and chemical properties, and the definition of the centigrade temperature scale set 100 °C as the boiling point of water at this pressure.
However, when the local water table height is within said five meters, the total stress felt five meters below the surface is decreased by the product of the height of the water table in to the five meter area, and the specific weight of water, 9.81 kN/m^3. This parameter is called the effective stress of the soil, basically equal to the ...