Pound-force
The pound-force is a non-SI unit of force or weight (properly abbreviated "lbf" or "lbf"). The pound-force is equal to a mass of one pound multiplied by the standard acceleration due to gravity on Earth (which is defined as exactly 9.806 65 m/s², or exactly 196,133/6096 ft/s², or approximately 32.174 05 ft/s²).
Though pounds-force had been used in low-precision measurements since the 18th century, they were never well-defined units until the 20th century. It was in 1901 when the CGPM first adopted a standard acceleration of gravity for the purpose of defining grams-force and kilograms-force, a value often borrowed to define pounds-force, though other values such as 32.16 ft/s² (9.80237 m/s²) have been used as well.
In SI units, a pound-force is equal to exactly 4.448 221 615 260 5 newtons, if the metric standard acceleration of gravity is borrowed for this purpose.
See pound for a more complete discussion of customary units of force and mass.
| Newton | Dyne | Kilopond | Pound-force | Poundal | |
|---|---|---|---|---|---|
| 1 N | := 1 kg·m/s² | = 105 dyn | ~= 0.10197 kp | ~= 0.22481 lbf | ~= 7.2330 pdl |
| 1 dyn | = 10−5 N | := 1 g·cm/s² | ~= 1.0197×10−6 kp | ~= 2.2481×10−6 lbf | ~= 7.2330×10−5 pdl |
| 1 kp | = 9.80665 N | = 980665 dyn | := gn·(1 kg) | ~= 2.2046 lbf | ~= 70.932 pdl |
| 1 lbf | = 4.4482216152605 N | ~= 444822 dyn | ~= 0.45359 kp | := gn·(1 lb) | ~= 32.174 pdl |
| 1 pdl | = 0.138254954376 N | ~= 13825 dyn | ~= 0.014098 kp | ~= 0.031081 lbf | := 1 lb·ft/s² |
| The values for the pound-force are calculated using the same value for the standard acceleration of gravity gn which is official for defining the kilopond (a.k.a. kilogram-force), something which is not required. Other values such as gn = 32.16 ft/s² are also used. | |||||
Categories: Units of force | Imperial units | Customary units in the United States