The pound-force is a non-SIunit of force or weight (properly abbreviated "lbf" or "lbf"). The pound-force is equal to a mass of one pound multiplied by the standard acceleration due to gravity on Earth (which is defined as exactly 9.806 65 m/s2, or exactly 196,133/6096 ft/s2, or approximately 32.174 05 ft/s2).
Though pounds-force had been used in low-precision measurements since the 18th century, they were never well-defined units until the 20th century. It was in 1901 when the CGPM first adopted a standard acceleration of gravity for the purpose of defining grams-force and kilograms-force, a value often borrowed to define pounds-force, though other values such as 32.16 ft/s² (9.80237 m/s²) have been used as well.
In SI units, a pound-force is equal to exactly 4.448 221 615 260 5 newtons, if the metric standard acceleration of gravity is borrowed for this purpose.
Seepound for a more complete discussion of customary units of force and mass.
Categories: Units of force | Imperial units | Customary units in the United States
The unit of force in the British gravitational system of units, approximately the force which a mass of 1 pound exerts on whatever it is resting on on the Earth; that is, the weight of a mass of 1 pound.
The weight of a mass of 1 pound varies from place to place; it weighs less at the equator than at the poles, and is lighter at high altitudes than at sea level.
The pound-force, however, is unvarying; it is defined as the weight (a force!) that a body with a mass of 1 pound would exert at a location where the acceleration due to gravity was exactly 32.
Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface.
At 1 lbf/inÂ², a force of one pound-force is applied to an area of one square inch.
In the United States, a kip is sometimes a unit of mass that equals 1,000 avoirdupois pounds (used to compute shipping charges), or more often a unit of force that equals 1,000 poundsforce (used to measure engineering loads).
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