Slug (unit)


The slug is a derived unit of mass in a weight-based system of measures, most notably within the British Imperial measurement system and in 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. A slug is defined as the mass that is accelerated by 1 ft/s2 when a force of one pound is exerted on it.
One slug has a mass of based on standard gravity, the international foot, and the avoirdupois pound. At the Earth's surface, an object with a mass of 1 slug exerts a force downward of approximately 32.2 lbf or.

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 20th century. Geepound was another name for this unit in early literature.
The name "slug" was coined before 1900 by British physicist Arthur Mason Worthington, but it did not see any significant use until decades later. A 1928 textbook says:
The slug is listed in the Regulations under the Weights and Measures Act, 1960. This regulation defines the units of weights and measures, both regular and metric, in Australia.

Related units

The blob is the inch version of the slug or equivalent to. This unit is also called slinch. Similar terms include slugette and snail.
Similar metric units include the glug in the centimetre–gram–second system, and the mug, par, or MTE in the metre–kilogram–second system.