Editing Kilogram-force (section)

==History==
The gram-force and kilogram-force were never well-defined units until the [[CGPM]] adopted a ''standard acceleration of gravity'' of 9.80665&nbsp;m/s<sup>2</sup> for this purpose in 1901,<ref>[https://www.bipm.org/en/committees/cg/cgpm/3-1901 Resolution of the 3rd CGPM (1901)]</ref> though they had been used in low-precision measurements of force before that time. Even then, the proposal to define kilogram-force as a standard unit of force was explicitly rejected.<ref name="CGPM3-P62">[https://www.bipm.org/utils/common/pdf/CGPM/CGPM3.pdf#page=62 Proceedings of the 3rd General Conference on Weights and Measures], 1901, pages 62–64 and 68, (french)</ref> Instead, the ''[[Newton (unit)|newton]]'' was proposed in 1913<ref name="CGPM5-p51">[https://www.bipm.org/utils/common/pdf/CGPM/CGPM5.pdf#page=51 Proceedings of the 5th General Conference on Weights and Measures], 1913, pages 51 and 56, (french)</ref> and accepted in 1948.<ref name="CGPM9-7">{{Cite web |url=https://www.bipm.org/en/CGPM/db/9/7/ |title=Resolution 7 of the 9th meeting of the CGPM (1948) |access-date=2021-03-02 |archive-date=2020-06-22 |archive-url=https://web.archive.org/web/20200622105030/https://www.bipm.org/en/CGPM/db/9/7/ |url-status=dead }}</ref>
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 (unit)|newton]].

Prior to this, the units were widely used in much of the world. They are still in use for some purposes; for example, they are used to specify tension of bicycle [[spoke]]s,<ref>{{cite web|url=http://ftp.cyclingnews.com/tech/fix/?id=tm_1|title=Balancing wheel tension with the TM-1 Spoke Tension Metre|quote=The recommended tension for spokes in bicycle wheels can be as low as 80 Kilograms force (Kfg) and as high as 230 Kilograms force. Author=Park Tool|author-link=Park Tool|publisher=Cyclingnews|access-date=2013-09-03}}</ref> [[draw weight]] of bows in [[archery]], and tensile strength of [[bond wire|electronics ''bond wire'']],<ref>{{Cite book |last=Harman |first=George G. |url=https://www.worldcat.org/oclc/609421363 |title=Wire Bonding in Microelectronics |date=2010 |publisher=McGraw-Hill |isbn=978-0-07-164265-1 |edition=3rd |location=New York |pages=408 |oclc=609421363 |quote=Breaking load (BL): The strength of a wire and its actual force (usually given in grams, grams-force, mN, etc.) required to break a particular wire in a tensile pull. It is not tensile strength, which by definition is the force per unit area.}}</ref> for informal references to pressure (as the technically incorrect ''kilogram per square centimetre'', omitting ''-force'', the kilogram''-force'' per square centimetre being the ''[[technical atmosphere]]'', the value of which is very near those of both the ''[[bar (unit)|bar]]'' and the ''standard atmosphere''), and to define the "[[metric horsepower]]" (PS) as 75 metre-kiloponds per second.<ref name="SP811"/> In addition, the kilogram force was the standard unit used for [[Vickers hardness test]]ing.<ref>{{Cite book |last=Callister |first=William D. Jr. |url=https://www.worldcat.org/oclc/401168960 |title=Materials Science and Engineering: An Introduction. |date=2010 |publisher=John Wiley & Sons, Inc. |others=David G. Rethwisch |isbn=978-0-470-41997-7 |edition=8th |location=Hoboken, NJ |oclc=401168960 |quote=In the past the units for Vickers hardness were kg/mm2; in Table 12.6 we use the SI units of GPa.}}</ref>
{{GravEngAbs|system=metric}}

In 1940s, Germany, the thrust of a rocket engine was measured in kilograms-force,{{citation needed|date=September 2020}} in the Soviet Union it remained the primary unit for thrust in the Russian space program until at least the late 1980s.{{citation needed|date=September 2020}} Dividing the thrust in kilograms-force on the mass of an engine or a rocket in kilograms conveniently gives the [[thrust to weight ratio]], dividing the thrust on propellant consumption rate ([[mass flow rate]]) in kilograms per second gives the [[specific impulse]] in seconds.

The term "kilopond" has been declared obsolete.<ref>European Economic Community, Council Directive of 18 October 1971 on the approximation of the laws of the Member States relating to units of measurement</ref>