User:Milton Beychok/Sandbox2: Difference between revisions
imported>Milton Beychok No edit summary |
imported>Milton Beychok No edit summary |
||
| Line 1: | Line 1: | ||
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>'''''). It is used primarily in the [[United States]] and is equivalent to exactly 4.4482216152605 [[newton]]s. | 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]]. | ||
==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><ref name=GCPM3/> and the internationally agreed upon definition of the pound-mass, denotes as '''''lbm''''', as being 0.45359237 kg<ref name=NBS/>, we have: | |||
:<math>\begin{align}1\,\mathrm{lbf} &= 1\,\mathrm{lbm} \cdot g_n \\ | |||
&= 0.45359237\,\mathrm{kg} \cdot 9.80665\,\mathrm{\tfrac{m}{s^2}}\\ | |||
&= 4.4482216152605\,\mathrm{N} (exactly)\end{align}</math> | |||
==Notes== | ==Notes== | ||
| Line 14: | Line 18: | ||
==References== | ==References== | ||
{{Reflist|refs= | |||
<ref name=GCPM3>[http://www.bipm.org/en/CGPM/db/3/2/ Resolution of the 3rd meeting of the CGPM (1901)]</ref> | |||
<ref name=NBS>[http://physics.nist.gov/Pubs/SP447/app8.pdf Appendix 8, Customary System of Weights and Measures] [[U.S. Dept. of Commerce]], Appendix 8, July 15, 1968.</ref> | |||
}} | |||
Revision as of 15:59, 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[1] and the internationally agreed upon definition of the pound-mass, denotes as lbm, as being 0.45359237 kg[2], we have:
Notes
- ↑ The symbol lbf is derived from the Latin libra for "pound" and the symbol f for "force")