Pressure

Pressure (symbol: p or P) is the <a href="/facts/Force/533Q1uzq">force</a> applied <a href="/facts/Perpendicular/u0k8xqx4">perpendicular</a> to the surface of an object per unit <a href="/facts/Area/KsNG1G9t">area</a> over which that force is distributed.: 445  <a href="/facts/Gauge_pressure/fJrvoTDU">Gauge pressure</a> (also spelled gage pressure) is the pressure relative to the ambient pressure.
Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the <a href="/facts/International_System_of_Units/S7YLglNz">SI</a> unit of pressure, the <a href="/facts/Pascal_(unit)/Am1To2Qm">pascal</a> (Pa), for example, is one <a href="/facts/Newton_(unit)/Ral9XgNl">newton</a> per <a href="/facts/Square_metre/u5nT9y0W">square metre</a> (N/m2); similarly, the <a href="/facts/Pound_(force)/w62gn6Y0">pound-force</a> per <a href="/facts/Square_inch/HMKj3Jok">square inch</a> (<a href="/facts/Pound_per_square_inch/RMdeTlB0">psi</a>, symbol lbf/in2) is the traditional unit of pressure in the <a href="/facts/Imperial_units/XBpM6M1W">imperial</a> and <a href="/facts/United_States_customary_units/s76n3Bx4">US customary</a> systems. Pressure may also be expressed in terms of <a href="/facts/Standard_atmosphere_(unit)/aTbYALII">standard atmospheric pressure</a>; the unit <a href="/facts/Atmosphere_(unit)/aTbYALII">atmosphere</a> (atm) is equal to this pressure, and the <a href="/facts/Torr/Y83YBu34">torr</a> is defined as 1⁄760 of this. <a href="/facts/Manometric/fJrvoTDU">Manometric</a> units such as the <a href="/facts/Centimetre_of_water/GIpSzIQa">centimetre of water</a>, <a href="/facts/Millimetre_of_mercury/qVG9oG1d">millimetre of mercury</a>, and <a href="/facts/Inch_of_mercury/jRv55tBk">inch of mercury</a> are used to express pressures in terms of the height of <a href="/facts/Pressure_measurement/fJrvoTDU">column of a particular fluid</a> in a manometer.

Pressure open-in-new

Pressure