Slug (unit)

Last updated
slug
Unit system British Gravitational system
Unit ofMass
Symbolslug
Conversions
1 slug in ...... is equal to ...
   BGS base units   1 ft−1⋅lbf⋅s2
   SI units   14.59390 kg
   US customary units   32.17404 lb

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 unit [1] (cf. poundal , a derived unit of force in a force-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. [2]

Contents

One slug is a mass equal to 32.17405  lb (14.59390  kg ) based on standard gravity, the international foot, and the avoirdupois pound. [3] In other words, at the Earth's surface (in standard gravity), an object with a mass of 1 slug weighs approximately 32.17405 lbf or 143.1173 N. [4] [5]

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. [6]

The name "slug" was coined before 1900 by British physicist Arthur Mason Worthington, [7] but it did not see any significant use until decades later. [8] It is derived from the meaning "solid block of metal" (cf. "slug" fake coin or "slug" projectile), not from the slug mollusc. [9] A 1928 textbook says:

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.

— Noel Charlton Little, College Physics, Charles Scribner's Sons, 1928, p. 165.
Three approaches to units of mass and force or weight [10] [11]
Base		ForceWeightMass
2nd law of motion m = F/aF = W⋅a/gF = m⋅a
System BG GM EE M AE CGS MTS SI
Acceleration (a)ft/s2m/s2ft/s2m/s2ft/s2 Gal m/s2m/s2
Mass (m) slug hyl pound-masskilogram pound gram tonne kilogram
Force (F),
weight (W)		 pound kilopond pound-forcekilopond poundal dyne sthène newton
Pressure (p) pound per square inch technical atmosphere pound-force per square inch standard atmosphere poundal per square foot barye pieze pascal

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.

The inch version of the slug (equal to 1 lbf⋅s2/in, or 12 slugs) has no official name, [3] but is commonly referred to as a blob, [12] slinch (a portmanteau of the words slug and inch), [13] [14] slugette, [15] or snail. [16] It is equivalent to 386.0886 pounds (175.1268 kg) based on standard gravity. [3]

Similar (but long-obsolete) metric units included the glug (980.665 g) in a gravitational system related to the centimetre–gram–second system, [17] [18] and the mug, hyl , par, or TME (German : technische Masseneinheit, lit.  'technical mass unit', 9.80665 kg) in a gravitational system related to the metre–kilogram–second system. [19]

See also

Related Research Articles

<span class="mw-page-title-main">Measurement</span> Process of assigning numbers to objects or events

Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared to a basic reference quantity of the same kind. The scope and application of measurement are dependent on the context and discipline. In natural sciences and engineering, measurements do not apply to nominal properties of objects or events, which is consistent with the guidelines of the International vocabulary of metrology published by the International Bureau of Weights and Measures. However, in other fields such as statistics as well as the social and behavioural sciences, measurements can have multiple levels, which would include nominal, ordinal, interval and ratio scales.

<span class="mw-page-title-main">Pound (mass)</span> Unit of mass

The pound or pound-mass is a unit of mass used in both the British imperial and United States customary systems of measurement. Various definitions have been used; the most common today is the international avoirdupois pound, which is legally defined as exactly 0.45359237 kilograms, and which is divided into 16 avoirdupois ounces. The international standard symbol for the avoirdupois pound is lb; an alternative symbol is lbm, #, and ℔ or ″̶.

<span class="mw-page-title-main">Pressure</span> Force distributed over an area

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure is the pressure relative to the ambient pressure.

<span class="mw-page-title-main">United States customary units</span> System of units of measurement commonly used in the United States

United States customary units form a system of measurement units commonly used in the United States and most U.S. territories, since being standardized and adopted in 1832. The United States customary system developed from English units that were in use in the British Empire before the U.S. became an independent country. The United Kingdom's system of measures was overhauled in 1824 to create the imperial system, which was officially adopted in 1826, changing the definitions of some of its units. Consequently, while many U.S. units are essentially similar to their imperial counterparts, there are noticeable differences between the systems.

<span class="mw-page-title-main">Weight</span> Force on a mass due to gravity

In science and engineering, the weight of an object, is the force acting on the object due to acceleration of gravity.

Specific impulse is a measure of how efficiently a reaction mass engine, such as a rocket using propellant or a jet engine using fuel, generates thrust.

<span class="mw-page-title-main">Metric system</span> Metre-based systems of measurement

The metric system is a decimal-based system of measurement. The current international standard for the metric system is the International System of Units, in which all units can be expressed in terms of seven base units: the metre, kilogram, second, ampere, kelvin, mole, and candela.

The pound of force or pound-force is a unit of force used in some systems of measurement, including English Engineering units and the foot–pound–second system.

The ounce is any of several different units of mass, weight, or volume and is derived almost unchanged from the uncia, an Ancient Roman unit of measurement.

The foot-pound force 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. The corresponding SI unit is the joule, though in terms of energy, one joule is not equal to one foot-pound.

The short ton is a measurement unit equal to 2,000 pounds (907.18 kg). It is commonly used in the United States, where it is known simply as a ton; however, the term is ambiguous, the single word "ton" being variously used for short, long, and metric tons.

The poundal is a unit of force, introduced in 1877, that is part of the Absolute English system of units, which itself is a coherent subsystem of the foot–pound–second system.

A system of units of measurement, also known as a system of units or system of measurement, is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Instances in use include the International System of Units or SI, the British imperial system, and the United States customary system.

The standard acceleration of gravity or standard acceleration of free fall, often called simply standard gravity and denoted by ɡ0 or ɡn, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is a constant defined by standard as 9.80665 m/s2. This value was established by the 3rd General Conference on Weights and Measures and used to define the standard weight of an object as the product of its mass and this nominal acceleration. The acceleration of a body near the surface of the Earth is due to the combined effects of gravity and centrifugal acceleration from the rotation of the Earth ; the total is about 0.5% greater at the poles than at the Equator.

The gravitational metric system is a non-standard system of units, which does not comply with the International System of Units (SI). It is built on the three base quantities length, time and force with base units metre, second and kilopond respectively. Internationally used abbreviations of the system are MKpS, MKfS or MKS . However, the abbreviation MKS is also used for the MKS system of units, which, like the SI, uses mass in kilogram as a base unit.

The foot–pound–second system is a system of units built on three fundamental units: the foot for length, the (avoirdupois) pound for either mass or force, and the second for time.

<span class="mw-page-title-main">Mass versus weight</span> Distinction between mass and weight

In common usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities. Nevertheless, one object will always weigh more than another with less mass if both are subject to the same gravity.

Some fields of engineering in the United States use a system of measurement of physical quantities known as the English Engineering Units. Despite its name, the system is based on United States customary units of measure.

<span class="mw-page-title-main">Coherence (units of measurement)</span> Type of system of units of measurement

A coherent system of units is a system of units of measurement used to express physical quantities that are defined in such a way that the equations relating the numerical values expressed in the units of the system have exactly the same form, including numerical factors, as the corresponding equations directly relating the quantities. It is a system in which every quantity has a unique unit, or one that does not use conversion factors.

<span class="mw-page-title-main">Imperial and US customary measurement systems</span> English (pre 1824), Imperial (post 1824) and US Customary (post 1776) units of measure

The imperial and US customary measurement systems are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.

References

  1. ↑ See Elementary High School physics and chemistry text books/fundamentals.
  2. ↑ Collins, Danielle (May 2019). "How to convert between mass and force — in metric and English units". Linear Motion Tips. Retrieved 18 January 2021.
  3. 1 2 3 Shigley, Joseph E. and Mischke, Charles R. Mechanical Engineering Design, Sixth ed, pp. 31–33. McGraw Hill, 2001. ISBN   0-07-365939-8.
  4. ↑ Beckwith, Thomas G., Roy D. Marangoni, et al. Mechanical Measurements, Fifth ed, pp. 34-36. Addison-Wesley Publishing, 1993. ISBN   0-201-56947-7.
  5. ↑ Shevell, R.S. Fundamentals of Flight, Second ed, p. xix. Prentice-Hall, 1989.
  6. ↑ gee Archived 2018-01-27 at the Wayback Machine . unit2unit.eu
  7. ↑ Worthington, Arthur Mason (1900). Dynamics of Rotation: An Elementary Introduction to Rigid Dynamics (3rd ed.). Longmans, Green, and Co. p. 9.
  8. ↑ Gyllenbok, Jan (April 11, 2018). Encyclopaedia of Historical Metrology, Weights, and Measures: Volume 1. Birkhäuser. ISBN   9783319575988 – via Google Books.
  9. ↑ Society, Digital Equipment Computer Users (September 4, 1965). "Papers and Presentations" – via Google Books.
  10. ↑ Comings, E. W. (1940). "English Engineering Units and Their Dimensions". Industrial & Engineering Chemistry. 32 (7): 984–987. doi:10.1021/ie50367a028.
  11. ↑ Klinkenberg, Adrian (1969). "The American Engineering System of Units and Its Dimensional Constant gc". Industrial & Engineering Chemistry. 61 (4): 53–59. doi:10.1021/ie50712a010.
  12. ↑ Norton, Robert L. Cam Design and Manufacturing Handbook, p. 13. Industrial Press Inc., 2009. ISBN   0831133678.
  13. ↑ Slug Archived 2016-11-30 at the Wayback Machine . DiracDelta Science & Engineering Encyclopedia
  14. ↑ "1 blob". Wolfram Alpha Computational Knowledge Engine. Retrieved 27 October 2011.
  15. ↑ Celmer, Robert. Notes to Accompany Vibrations II. Version 2.2. 2009.
  16. ↑ Rowlett, Russ. "How Many? A Dictionary of Units of Measurement". unc.edu, September 1, 2004. Retrieved January 26, 2018.
  17. ↑ Cardarelli, François (1999). Encyclopaedia of Scientific Units, Weights and Measures . Springer. pp.  358, 377. ISBN   1-85233-682-X.
  18. ↑ David, A. (1958). "Beware of the "Glug," a New Unit of Mass!". Letters to the Editor. American Journal of Physics. 26 (1): 41. doi:10.1119/1.1934599.
  19. ↑ Cardarelli, François (1999). Encyclopaedia of Scientific Units, Weights and Measures . Springer. pp.  470, 497. ISBN   1-85233-682-X.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.