User:Milton Beychok/Sandbox2: Difference between revisions
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The '''pound-force''' (symbol: '''lbf''' <ref name=lbf group= | The '''pound-force''' (symbol: '''lbf''' <ref name=lbf group=note/> ) is a [[measurement]] unit of [[force]] which will [[acceleration|accelerate]] 1 [[Pound (mass)|pound]] of [[mass]] to 9.80665 [[metre|m]]/[[second|s]]<sup>2</sup> (≈ 32.17405 [[foot|ft]]/[[second|s]]<sup>2</sup>), the standard average [[acceleration due to gravity]] on [[Earth]]'s surface (referred to as '''''g<sub>n</sub>''''' <ref name=GCPM3/>). It is used primarily in the [[United States]] and is equivalent to exactly 4.4482216152605 [[newton]]s. | ||
In common usage and other contexts, it is most often referred to in the United States as a '''''pound''''' or as '''''lb''''', but this can lead to confusion with the [[pound (mass)|pound-mass]]. | In common usage and other contexts, it is most often referred to in the United States as a '''''pound''''' or as '''''lb''''', but this can lead to confusion with the [[pound (mass)|pound-mass]]. | ||
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==Definition in terms of the SI unit of force== | ==Definition in terms of the SI unit of force== | ||
The newton (symbol: N) is the unit of force named in the [[International System of Units]] (SI). Using the standard average acceleration due to gravity, denoted '''''g<sub>n</sub>''''', as being 9.80665 m/s<sup>2</sup> and the internationally agreed upon definition of the pound-mass, | The newton (symbol: N) is the unit of force named in the [[International System of Units]] (SI). Using the standard average acceleration due to gravity, denoted '''''g<sub>n</sub>''''', as being 9.80665 m/s<sup>2</sup> and the internationally agreed upon definition of the pound-mass, denoted as '''''lbm''''', as being 0.45359237 [[Kilogram|kg]],<ref name=GCPM3/><ref name=NBS/> we can determine the number of newtons exactly equivalent to a pound-force: | ||
:<math>\begin{align}1\,\mathrm{lbf} &\equiv 1\,\mathrm{lbm} \cdot g_n \\ | :<math>\begin{align}1\,\mathrm{lbf} &\equiv 1\,\mathrm{lbm} \cdot g_n \\ | ||
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*1 lbf ≈ 4448822 [[dyne]] (symbol: '''dyn''') | *1 lbf ≈ 4448822 [[dyne]] (symbol: '''dyn''') | ||
*1 lbf ≈ 0.453592 [[kilogram-force]] (symbol: '''kgf''') | *1 lbf ≈ 0.453592 [[kilogram-force]] (symbol: '''kgf''') | ||
*1 lbf ≈ 0.453592 [[Kilogram-force|kilopond]] (symbol: '''kp''') | *1 lbf ≈ 0.453592 [[Kilogram-force|kilopond]] (symbol: '''kp''')<ref name=kp group=note/> | ||
*1 lbf ≈ 4.448221×10<sup>−3</sup> [[sthène]] (symbol: '''sn''') | *1 lbf ≈ 4.448221×10<sup>−3</sup> [[sthène]] (symbol: '''sn''') | ||
*1 lbf ≈ 32.17405 [[poundal]] (symbol: '''pdl''') | *1 lbf ≈ 32.17405 [[poundal]] (symbol: '''pdl''') | ||
*1 lbf ≡ 0.001 [[kip]] (symbol: '''kip''') | *1 lbf ≡ 0.001 [[kip]] (symbol: '''kip''')<ref name=kip group=note/> | ||
==Notes== | ==Notes== | ||
{{ | {{reflist|group=note|refs= | ||
<ref name=lbf group= | <ref name=lbf group=note>The symbol '''lbf''' is derived from the Latin ''libra'' for "pound" and the symbol ''f'' for "force")</ref> | ||
<ref name=kp group=note> Another name for a kilogram-force. Not to be confused with "kilopounds", meaning 1,000 pounds of mass.</ref> | |||
<ref name=kip group=note>A non-SI unit of force equal to 1,000 pound-force.</ref> | |||
}} | }} | ||
Revision as of 22:21, 5 July 2011
The pound-force (symbol: lbf [note 1] ) is a measurement unit of force which will accelerate 1 pound of mass to 9.80665 m/s2 (≈ 32.17405 ft/s2), the standard average acceleration due to gravity on Earth's surface (referred to as gn [1]). It is used primarily in the United States and is equivalent to exactly 4.4482216152605 newtons.
In common usage and other contexts, it is most often referred to in the United States as a pound or as lb, but this can lead to confusion with the pound-mass.
Definition in terms of the SI unit of force
The newton (symbol: N) is the unit of force named in the International System of Units (SI). Using the standard average acceleration due to gravity, denoted gn, as being 9.80665 m/s2 and the internationally agreed upon definition of the pound-mass, denoted as lbm, as being 0.45359237 kg,[1][2] we can determine the number of newtons exactly equivalent to a pound-force:
Equivalent units of force
- 1 lbf ≈ 4.448221 newton (symbol: N)
- 1 lbf ≈ 4448822 dyne (symbol: dyn)
- 1 lbf ≈ 0.453592 kilogram-force (symbol: kgf)
- 1 lbf ≈ 0.453592 kilopond (symbol: kp)[note 2]
- 1 lbf ≈ 4.448221×10−3 sthène (symbol: sn)
- 1 lbf ≈ 32.17405 poundal (symbol: pdl)
- 1 lbf ≡ 0.001 kip (symbol: kip)[note 3]
Notes
References
- ↑ Jump up to: 1.0 1.1 Resolution of the 3rd meeting of the CGPM (1901) Definition of the standard average acceleration due to gravity
- ↑ Appendix 8, Customary System of Weights and Measures U.S. Dept. of Commerce, July 15, 1968. Definition of the pound-mass.