World Library  
Flag as Inappropriate
Email this Article

Slug (mass)

Article Id: WHEBN0000902982
Reproduction Date:

Title: Slug (mass)  
Author: World Heritage Encyclopedia
Language: English
Subject: Pound (force), Poundal, Imperial units, United States customary units, Conversion of units
Collection: Imperial Units, Units of Mass
Publisher: World Heritage Encyclopedia

Slug (mass)

The slug is a unit of mass associated with Imperial units and United States customary units. It is a mass that accelerates by 1 ft/s2 when a force of one pound (lbF) is exerted on it.

1\,\text{slug} =1\,\frac{\text{lb}_F\cdot\text{s}^2}{\text{ft}} \qquad\Longleftrightarrow\qquad 1\,\text{lb}_F = 1\,\frac{\text{slug}\cdot\text{ft}}{\text{s}^2}

One slug has a mass of 32.174049 lbm or 14.593903 kg based on standard gravity, the international foot, and the avoirdupois pound.[1] At the surface of the Earth, an object with a mass of 1 slug exerts a force of approximately 32.2 lbF or 143 N.[2][3]


  • History 1
  • Similar units 2
  • References 3
  • External links 4


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 20th century. Geepound was another name for this unit in early literature.[4]

The name "slug" was coined before 1900 by British physicist Arthur Mason Worthington,[5] but it did not see any significant use until decades later. 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 mass and force units[6][7]
Base force, length, time weight, length, time mass, length, time
Force (F) F = ma = wa/g F = ma/gc = wa/g F = ma = wa/g
Weight (w) w = mg w = mg/gcm w = mg
Acceleration (a) ft/s2 m/s2 ft/s2 m/s2 ft/s2 Gal m/s2 m/s2
Mass (m) slug hyl lbm kg lb g t kg
Force (F) lb kp lbF kp pdl dyn sn N
Pressure (p) lb/in2 at PSI atm pdl/ft2 Ba pz Pa

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.

Similar units

The blob is the inch version of the slug (1 blob = 1 lbf·s2/in = 12 slugs)[1] or equivalent to 175.126 kg. This unit is also called slinch (a portmanteau of the words slug and inch).[8][9] Similar terms include slugette,[10] and a snail.[11]

Similar metric units include the "glug" in the centimetre-gram-second system, and the "mug", "par", or "MTE" in the metre-kilogram-second system.[12]


  1. ^ a b Shigley, Joseph E. and Mischke, Charles R. Mechanical Engineering Design, Sixth ed, pp. 31–33. McGraw Hill, 2001. ISBN 0-07-365939-8.
  2. ^ Beckwith, Thomas G., Roy D. Marangoni, et al. Mechanical Measurements, Fifth ed, pp. 34-36. Addison-Wesley Publishing, 1993. ISBN 0-201-56947-7.
  3. ^ Shevell, R.S. Fundamentals of Flight, Second ed, p. xix. Prentice-Hall, 1989.
  4. ^ [1].
  5. ^ Worthington, Arthur Mason (1900). Dynamics of Rotation: An Elementary Introduction to Rigid Dynamics (3rd ed.). Longmans, Green, and Co. p. 9. 
  6. ^ Michael R. Lindeburg (2011). Civil Engineering Reference Manual for the Pe Exam. Professional Publications.  
  7. ^ Wurbs, Ralph A, Fort Hood Review Sessions for Professional Engineering Exam (PDF), retrieved October 26, 2011 
  8. ^ Slug. DiracDelta Science & Engineering Encyclopedia
  9. ^ "1 blob". Wolfram Alpha Computational Knowledge Engine. Retrieved 27 October 2011. 
  10. ^ Celmer, Robert. Notes to Accompany Vibrations II. Version 2.2. 2009.
  11. ^ [2]
  12. ^ Cardarelli, François (1999). Scientific Units, Weights and Measures. Springer. pp. 358, 377.  

External links

  • "What is a Slug?" on
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.