slug (unit)
{{for|the railway locomotive|Slug (railroad)}}
{{Short description|Unit of mass}}
{{Infobox unit
|name = slug
|image =
|caption =
|standard = British Gravitational system
|quantity = Mass
|symbol = slug
|symbol2 =
|namedafter =
|extralabel =
|extradata =
|units1 = BGS base units
|inunits1 = 1 ft−1⋅lbf⋅s2
|units2 = SI units
|inunits2 = 14.59390 kg
|units3 = US customary units
|inunits3 = {{cvt|14.59390|kg|disp=out|sigfig=7}}
}}
The slug is a derived unit of mass in a weight-based system of measures, most notably within the British Imperial measurement system and the United States customary measures system. Systems of measure either define mass and derive a force unit or define a base force and derive a mass unitSee Elementary High School physics and chemistry text books/fundamentals. (cf. poundal, a derived unit of force in a mass-based system). A slug is defined as a mass that is accelerated by 1 ft/s2 when a net force of one pound (lbf) is exerted on it.{{cite web |last1=Collins |first1=Danielle |title=How to convert between mass and force — in metric and English units |url=https://www.linearmotiontips.com/how-to-convert-between-mass-and-force-in-metric-and-english-units/ |website=Linear Motion Tips |date=May 2019 |access-date=18 January 2021}}
:
1~\text{slug}= 1~\text{lbf}{\cdot}\frac{\text{s}^2}{\text{ft}}
\quad\Longleftrightarrow\quad
1~\text{lbf}= 1~\text{slug}{\cdot}\frac{\text{ft}}{\text{s}^2}
One slug is a mass equal to {{convert|32.17405|lb|kg|lk=on|abbr=on}} based on standard gravity, the international foot, and the avoirdupois pound.Shigley, Joseph E. and Mischke, Charles R. Mechanical Engineering Design, Sixth ed, pp. 31–33. McGraw Hill, 2001. {{ISBN|0-07-365939-8}}. In other words, at the Earth's surface (in standard gravity), an object with a mass of 1 slug weighs approximately {{cvt|32.17405|lbf|N|disp=or}}.Beckwith, Thomas G., Roy D. Marangoni, et al. Mechanical Measurements, Fifth ed, pp. 34-36. Addison-Wesley Publishing, 1993. {{ISBN|0-201-56947-7}}.Shevell, R.S. Fundamentals of Flight, Second ed, p. xix. Prentice-Hall, 1989.
History
The slug is part of a subset of units known as the gravitational FPS system, one of several such specialized systems of mechanical units developed in the late 19th and the early 20th century. Geepound was another name for this unit in early literature.[http://www.unit2unit.eu/lb_gee.html gee] {{Webarchive|url=https://web.archive.org/web/20180127202421/http://unit2unit.eu/lb_gee.html |date=2018-01-27 }}. unit2unit.eu
The name "slug" was coined before 1900 by British physicist Arthur Mason Worthington,{{cite book |author= Worthington, Arthur Mason |title= Dynamics of Rotation: An Elementary Introduction to Rigid Dynamics |publisher= Longmans, Green, and Co. |year= 1900 |edition= 3rd |page= 9 |url= https://archive.org/stream/dynamicsofrotati00wortuoft#page/8/mode/2up}} but it did not see any significant use until decades later.{{Cite book|url=https://books.google.com/books?id=XnRVDwAAQBAJ&q=%22Arthur+Mason+Worthington%22+slug&pg=PA207|title=Encyclopaedia of Historical Metrology, Weights, and Measures: Volume 1|first=Jan|last=Gyllenbok|date=April 11, 2018|publisher=Birkhäuser|isbn=9783319575988|via=Google Books}} It is derived from the meaning "solid block of metal" (cf. "slug" fake coin or "slug" projectile), not from the slug mollusc.{{Cite web|url=https://books.google.com/books?id=9E4gAQAAIAAJ&q=%22solid+block+of+metal.%22+slug|title=Papers and Presentations|first=Digital Equipment Computer Users|last=Society|date=September 4, 1965|via=Google Books}} A 1928 textbook says:
{{quote|text=No name has yet been given to the unit of mass and, in fact, as we have developed the theory of dynamics no name is necessary. Whenever the mass, m, appears in our formulae, we substitute the ratio of the convenient force-acceleration pair (w/g), and measure the mass in lbs. per ft./sec.2 or in grams per cm./sec.2.|author=Noel Charlton Little, College Physics, Charles Scribner's Sons, 1928, p. 165.}}
{{GravEngAbs}}
The slug is listed in the Regulations under the Weights and Measures (National Standards) Act, 1960. This regulation defines the units of weights and measures, both regular and metric, in Australia.
Related units
The inch version of the slug (equal to 1 lbf⋅s2/in, or 12{{nbsp}}slugs) has no official name, but is commonly referred to as a blob,Norton, Robert L. [https://books.google.com/books?id=fK_Q3XNEpMAC&q=blob+mass&pg=PA13 Cam Design and Manufacturing Handbook, p. 13.] Industrial Press Inc., 2009. {{ISBN|0831133678}}. slinch (a portmanteau of the words slug and inch),[http://www.diracdelta.co.uk/science/source/s/l/slug/source.html Slug] {{Webarchive|url=https://web.archive.org/web/20161130034640/http://www.diracdelta.co.uk/science/source/s/l/slug/source.html |date=2016-11-30 }}. DiracDelta Science & Engineering Encyclopedia{{cite web |title=1 blob |url=http://www.wolframalpha.com/input/?i=1+blob&lk=1 |work=Wolfram Alpha Computational Knowledge Engine |access-date=27 October 2011}} slugette,Celmer, Robert. Notes to Accompany Vibrations II. Version 2.2. 2009. or snail.Rowlett, Russ. [http://www.unc.edu/~rowlett/units/dictS.html "How Many? A Dictionary of Units of Measurement"]. unc.edu, September 1, 2004. Retrieved January 26, 2018. It is equivalent to {{convert|386.0886|lb}} based on standard gravity.
Similar (but long-obsolete) metric units included the glug (980.665 g) in a gravitational system related to the centimetre–gram–second system,{{cite book |last=Cardarelli |first=François |title=Encyclopaedia of Scientific Units, Weights and Measures |url=https://archive.org/details/encyclopaediaofs0000card |url-access=registration |pages=[https://archive.org/details/encyclopaediaofs0000card/page/358 358], 377 |year=1999 |publisher=Springer |isbn=1-85233-682-X}}{{cite journal |title= Beware of the "Glug," a New Unit of Mass! |year= 1958 |last1= David |first1= A. |journal= American Journal of Physics |volume= 26 |issue= 1 |page= 41 |department= Letters to the Editor |doi= 10.1119/1.1934599 }} and the mug, hyl, par, or TME ({{Langx|de|technische Masseneinheit|lit=technical mass unit}}, 9.80665 kg) in a gravitational system related to the metre–kilogram–second system.{{cite book |last=Cardarelli |first=François |title=Encyclopaedia of Scientific Units, Weights and Measures |url=https://archive.org/details/encyclopaediaofs0000card |url-access=registration |pages=[https://archive.org/details/encyclopaediaofs0000card/page/470 470], 497 |year=1999 |publisher=Springer |isbn=1-85233-682-X}}
See also
References
{{Reflist}}
External links
- [http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/slug.html "What is a Slug?" on phy-astr.gsu.edu]
{{Imperial units}}
Category:Customary units of measurement in the United States