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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 ]
fps 2: ≡ 1 ft/s 2 = 3.048 × 10 −1 m/s 2: gal; galileo: Gal ≡ 1 cm/s 2 = 10 −2 m/s 2: inch per minute per second: ipm/s ≡ 1 in/(min⋅s) = 4.2 3 × 10 −4 m/s 2: inch per second squared: ips 2: ≡ 1 in/s 2 = 2.54 × 10 −2 m/s 2: knot per second: kn/s ≡ 1 kn/s ≈ 5.1 4 × 10 −1 m/s 2: metre per second squared (SI unit) m/s 2 ...
The unit of substance in the FPS system is the pound-mole (lb-mol) = 273.16 × 10 24. Until the SI decided to adopt the gram-mole, the mole was directly derived from the mass unit as (mass unit)/(atomic mass unit). The unit (lbf⋅s 2 /ft)-mol also appears in a former definition of the atmosphere.
The pound-force is the product of one avoirdupois pound (exactly 0.45359237 kg) and the standard acceleration due to gravity, approximately 32.174049 ft/s 2 (9.80665 m/s 2). [ 5 ] [ 6 ] [ 7 ] The standard values of acceleration of the standard gravitational field ( g n ) and the international avoirdupois pound (lb) result in a pound-force equal ...
In unit systems where force is a derived unit, like in SI units, g c is equal to 1. In unit systems where force is a primary unit, like in imperial and US customary measurement systems , g c may or may not equal 1 depending on the units used, and value other than 1 may be required to obtain correct results. [ 2 ]
1 board-foot = 1 ft × 1 ft × 1 in = 2.360 dm 3; Mass 1 slug = 1 lbf⋅s 2 /ft ≈ 14.59390 kg; Force 1 poundal = force to accelerate 1 pound mass 1 foot/second/second ≈ 0.138 newtons. 1 kip = 1000 lbf ≈ 4.44822 kN; Energy 1 foot-pound ≈ 1.356 J
Since a pound of force (pound force) accelerates a pound of mass at 32.174 049 ft/s 2 (9.80665 m/s 2; the acceleration of gravity, g), we can scale down the unit of force to compensate, giving us one that accelerates 1 pound mass at 1 ft/s 2 rather than at 32.174 049 ft/s 2; and that is the poundal, which is approximately 1 ⁄ 32 pound force.
Units for other physical quantities are derived from this set as needed. In English Engineering Units, the pound-mass and the pound-force are distinct base units, and Newton's Second Law of Motion takes the form = where is the acceleration in ft/s 2 and g c = 32.174 lb·ft/(lbf·s 2).