# Kilogram-force

Kilogram-force

A kilogram-force (kgf or kgF), or kilopond (kp, from latin pondus meaning weight), is a gravitational metric unit of force. It is equal to the magnitude of the force exerted by one kilogram of mass in a 9.80665 m/s2 gravitational field (standard gravity, a conventional value approximating the average magnitude of gravity on Earth).[1] Therefore one kilogram-force is by definition equal to 9.8066N.[2][3] Similarly, a gram-force is 9.80665 mN, and a milligram-force is 9.80665 µN.

## History

The gram-force and kilogram-force were never well-defined units until the CGPM adopted a standard acceleration of gravity of 980.665 cm/s2 for this purpose in 1901, though they had been used in low-precision measurements of force before that time. The kilogram-force has never been a part of the International System of Units (SI), which was introduced in 1960. The SI unit of force is the newton.

Prior to this, the unit was widely used in much of the world and it is still in use for some purposes. The thrust of a rocket engine, for example, was measured in kilograms-force in 1940s Germany, in the Soviet Union (where it remained the primary unit for thrust in the Russian space program until at least the late 1980s), and it is still used today in China and sometimes by the European Space Agency.

It is also used for tension of bicycle spokes, for torque measured in "meter-kilograms", for informal references to pressure in kilograms per square centimeter (1 kp/cm² = 1 at ≈ 1 bar ≈ 1 atm), for the draw weight of bows in archery, and to define the "metric horsepower" (PS) as 75 metre-kiloponds per second[2] or the technical atmosphere (at) as 1 kilopond per square centimetre.

Three approaches to mass and force units[4] v · d · e
Base force, length, time weight, length, time mass, length, time
Designations gravitational, technical colloquial, pre-newtonian absolute, scientific
Type coherent incoherent coherent
Force (F) $F = m\cdot {a} = w\cdot\tfrac{a}{g}$ $F = m\cdot\tfrac{a}{g_c} = w\cdot\tfrac{a}{g}$ $F = m\cdot {a} = w\cdot\tfrac{a}{g}$
Weight (w) $w = m\cdot g$ $w = m\cdot\tfrac{g}{g_c} \approx m$ $w = m\cdot g$
System BG GM EE EM AE CGS MTS SI
Acceleration (a) ft/s2 m/s2 ft/s2 m/s2 ft/s2 gal m/s2 m/s2
Mass (m) slug hyl lbm kg lb g t kg
Force (F) lb kp lbF kp pdl dyn sn N
Pressure (p) lb/in2 (PSI) at lbF/in2 (PSI) atm pdl/in2 Ba pz Pa

## Related units

A tonne-force, metric ton-force, megagram-force, or megapond (Mp) are 1000 kilograms-force.

The decanewton or dekanewton (daN) is used in some fields as an approximation to the kilogram-force, being exactly rather than approximately 10 newtons.

Units of force
v · d · e newton
(SI unit)
dyne kilogram-force,
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 ≈ 4.448222 N ≈ 444822 dyn ≈ 0.45359 kp gn·(1 lb) ≈ 32.174 pdl
1 pdl ≈ 0.138255 N ≈ 13825 dyn ≈ 0.014098 kp ≈ 0.031081 lbF ≡ 1 lb·ft/s²
The value of gn as used in the official definition of the kilogram-force is used here for all gravitational units.

## References

1. ^ The international system of units (SI)United States Department of Commerce, NIST Special Publication 330, 2008, p. 52
2. ^ a b NIST Guide for the Use of the International System of Units (SI) Special Publication 811, (1995) page 51
3. ^ BIPM SI brochure, chapter 2.2.2.
4. ^ Lindeburg, Michael, Civil Engineering Reference Manual for the PE Exam

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### Look at other dictionaries:

• kilogram-force — jėgos kilogramas statusas T sritis Standartizacija ir metrologija apibrėžtis Nesisteminis jėgos matavimo vienetas: 1 kgf = 9,80665 N (tiksliai). atitikmenys: angl. kilogram force vok. Kilopond, n rus. килограмм сила, f pranc. kilogramme force, m …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

• kilogram-force — jėgos kilogramas statusas T sritis Energetika apibrėžtis Kilogramas, lygus jėgai, kuri 1 kilogramo masei suteikia 9,80665 m/s² pagreitį.1 kgf (kG) – 9,80665 N. atitikmenys: angl. kilogram force vok. Kilogramm Kraft, n rus. килограмм сила, m pranc …   Aiškinamasis šiluminės ir branduolinės technikos terminų žodynas

• Kilogram-force per square centimetre — A kilogram force per square centimeter (kgf/cm2), often just kilogram per square centimeter (kg/cm2), is a unit of pressure using metric units. Its use is now deprecated; it is not a part of the International System of Units (SI), the modern… …   Wikipedia

• kilogram (force) per square centimeter — (kgf/cm2 or kg/cm2 or kgsc)    a common metric unit of pressure equal to 98.0665 kilopascals (see below) or about 14.2234 pounds per square inch (lbf/in2 or psi). Similarly, one kilogram force per square meter is equal to 9.806 65 pascals …   Dictionary of units of measurement

• kilogram force — (kgf)    a unit of force equal to the gravitational force on a mass of one kilogram.    One kilogram of force equals 9.806 65 newtons, or 2.204 622 6 pounds of force in the traditional English system. Using this unit revives the old confusion… …   Dictionary of units of measurement

• kilogram-force — /kil euh gram fawrs , fohrs /, n. Physics. a meter kilogram second unit of force, equal to the force that produces an acceleration equal to the acceleration of gravity, when acting on a mass of one kilogram. Abbr.: kgf Cf. newton. [1955 60] * * * …   Universalium

• kilogram-force — /kil euh gram fawrs , fohrs /, n. Physics. a meter kilogram second unit of force, equal to the force that produces an acceleration equal to the acceleration of gravity, when acting on a mass of one kilogram. Abbr.: kgf Cf. newton. [1955 60] …   Useful english dictionary

• kilogram-force — (Physics) unit of force that causes acceleration that is equal to the acceleration of gravity on one kilogram of mass …   English contemporary dictionary

• kilogram-force — /kɪləgræm ˈfɔs/ (say kiluhgram faws) noun a non SI unit of force, equal to 9.80665 newtons. Symbol: kgf …

• Kilogram — Kg redirects here. For other uses, see Kg (disambiguation). Kilogram A computer generated image of the international prototype kilogram (IPK). The IPK is the kilogram. The IPK, which is roughly the size of a golf ball, sits here alongside a ruler …   Wikipedia