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This is convenient because one pound mass exerts one pound force due to gravity. Note, however, unlike the other systems the force unit is not equal to the mass unit multiplied by the acceleration unit [ 11 ] —the use of Newton's second law , F = m ⋅ a , requires another factor, g c , usually taken to be 32.174049 (lb⋅ft)/(lbf⋅s 2 ).
The unit of substance in the FPS system is the pound-mole (lb-mol) = 273.16 × 1024. Until the SI decided to adopt the gram-mole, the mole was directly derived from the mass unit as (mass unit)/ (atomic mass unit). The unit (lbf⋅s 2 /ft)-mol also appears in a former definition of the atmosphere.
Gravitational metric system. ≈ 0.1382550 kgf⋅m. A pound-foot (lb⋅ft), abbreviated from pound-force foot (lbf · ft), is a unit of torque representing one pound of force acting at a perpendicular distance of one foot from a pivot point. [2] Conversely one foot pound-force (ft · lbf) is the moment about an axis that applies one pound-force ...
CGS units. 13,558,180 erg. The foot-pound force (symbol: ft⋅lbf, [1] ft⋅lbf, [2] or ft⋅lb [3]) is a unit of work or energy in the engineering and gravitational systems in United States customary and imperial units of measure. It is the energy transferred upon applying a force of one pound-force (lbf) through a linear displacement of one foot.
See Weight for detail of mass/weight distinction and conversion. Avoirdupois is a system of mass based on a pound of 16 ounces, while Troy weight is the system of mass where 12 troy ounces equals one troy pound. The symbol g 0 is used to denote standard gravity in order to avoid confusion with the (upright) g symbol for gram.
absolute temperature. degree Rankine (°R) kelvin (K) 5 / 9 K. Units for other physical quantities are derived from this set as needed. In English Engineering Units, the pound-mass and the pound-force are distinct base units, and Newton's Second Law of Motion takes the form where is the acceleration in ft/s 2 and g c = 32.174 lb·ft/ (lbf·s2).
When a distinction is necessary, the term pound-force may refer to a unit of force rather than mass. The troy pound (373.241 7216 g) was made the primary unit of mass by the Weights and Measures Act 1824 and its use was abolished in the UK on 1 January 1879, [30] with only the troy ounce (31.103 4768 g) and its decimal subdivisions retained. [31]
The avoirdupois pound is legally defined as a measure of mass, [24] but the name pound is also applied to measures of force. For instance, in many contexts, the pound avoirdupois is used as a unit of mass, but in some contexts, the term "pound" is used to refer to "pound-force". The slug is another unit of mass derived from pound-force.