The 'slug' is an
English unit of
mass. It is a mass that accelerates by 1 ft/s
2 when a force of one
pound-force (lb
f) is exerted on it. Therefore a slug has a mass of about 32.17405
pound-mass or 14.5939 kg, depending on the chosen value of
gN.
; 1 slug := 1
lbf·s²/ft
The slug is part of a subset of coherent units known as the gravitational
foot-pound-second system (FPS), one of several such specialized systems of mechanical units developed in the late 19th and the 20th century. The slug was first used in 1902 by
Arthur Mason Worthington (1852–1916) in ''Dynamics of Rotation'' (
OED).
Another name for this unit in early literature is the 'geepound'.
The term 'metric slug' appears as a footnote in the 1967 seventh edition of ''Marks Standard Handbook for Mechanical Engineers''. The term is sometimes collapsed to 'mug' and it is also called the 'TME' (German: ''technische Masseneinheit'', technical mass unit). It is the mass that accelerates at 1 m/s
2 under a force of 1
kgf. Because 1 kg
f = 9.806 65
N, the metric slug is 9.806 65 kilograms. This has also been called the 'hyl', but there is an alternate definition of the hyl equalling 9.806 65 grams which would make the kilohyl equal to the TME.
| Systems | Gravitational | Engineering | Absolute |
|---|
| Newton’s second law | ''F = m·a'' | ''F = m·a/gc = w·a/g'' | ''F = m·a'' |
|---|---|
| Weight of an object | ''w = m·g'' | ''w = m·g/gc'' | ''w = m·g'' |
|---|---|
| Units | English | Metric | English | Metric | English | Metric |
|---|---|
| Time | s | s | s | s | s | s |
|---|---|
| Distance | ft | m | ft | m | ft | m |
|---|---|
| Mass | slug | hyl | pound-mass | kilogram | pound | kilogram |
|---|---|
| Force | pound | kilopond | pound-force | kilopond | poundal | newton |
|---|---|
Trivia
In the film ''An Officer and a Gentleman'' Richard Gere plays a trainee naval aviator attending Naval Officer Training School. In one scene he is being taught aerodynamics, where the density of air is quoted by the instructor in 'slugs per cubic foot'.
External links
★
Newtons, Slugs and Kilograms Force for a detailed mathematical explanation