User:Milton Beychok/Sandbox2: Difference between revisions
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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 | 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, denotes as '''''lbm''''', as being 0.45359237 kg:<ref name=GCPM3/><ref name=NBS/> | ||
:<math>\begin{align}1\,\mathrm{lbf} & | :<math>\begin{align}1\,\mathrm{lbf} &\equiv 1\,\mathrm{lbm} \cdot g_n \\ | ||
& | &\equiv 0.45359237\,\mathrm{kg} \cdot 9.80665\,\mathrm{\tfrac{m}{s^2}}\\ | ||
& | &\equiv 4.4482216152605\,\mathrm{N} \end{align}</math> | ||
==Notes== | ==Notes== | ||
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{{Reflist|refs= | {{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=GCPM3>[http://www.bipm.org/en/CGPM/db/3/2/ Resolution of the 3rd meeting of the CGPM (1901)] Definition of the standard average acceleration due to gravity</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]] | <ref name=NBS>[http://physics.nist.gov/Pubs/SP447/app8.pdf Appendix 8, Customary System of Weights and Measures] [[U.S. Dept. of Commerce]], July 15, 1968. Definition of the pound-mass.</ref> | ||
}} | }} | ||
Revision as of 16:11, 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, denotes as lbm, as being 0.45359237 kg:[1][2]
Notes
- ↑ The symbol lbf is derived from the Latin libra for "pound" and the symbol f for "force")
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.