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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 ]
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.
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 ...
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).
foot-pound-force per hour: ft⋅lbf/h ≡ 1 ft lbf/h ≈ 3.766 161 × 10 −4 W: foot-pound-force per minute: ft⋅lbf/min ≡ 1 ft lbf/min = 2.259 696 580 552 334 × 10 −2 W: foot-pound-force per second: ft⋅lbf/s ≡ 1 ft lbf/s = 1.355 817 948 331 4004 W: horsepower (boiler) hp ≈ 34.5 lb/h × 970.3 BTU IT /lb ≈ 9 809.5 W [35 ...
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.
It is a constant defined by standard as 9.806 65 m/s 2 (about 32.174 05 ft/s 2). This value was established by the third General Conference on Weights and Measures (1901, CR 70) and used to define the standard weight of an object as the product of its mass and this nominal acceleration .
The conversion for the poundal is given by 1 pdl = 1 lb·ft/s 2 = 0.138 254 954 376 N (precisely). [1] To convert between the absolute and gravitational FPS systems one needs to fix the standard acceleration g which relates the pound to the pound-force. [citation needed] =