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The kilogram-force (kgf or kg''F''), 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 gravitational field (standard gravity, a conventional value approximating the average magnitude of gravity on Earth).〔(''The international system of units (SI)'' ) – United States Department of Commerce, NIST Special Publication 330, 2008, p. 52〕 Therefore one kilogram-force is by definition equal to .〔NIST (''Guide for the Use of the International System of Units (SI)'' ) Special Publication 811, (1995) page 51〕〔(BIPM SI brochure ), chapter 2.2.2.〕 Similarly, a gram-force is , and a milligram-force is . One kilogram-force is approximately 2.204622 pounds-force. Kilogram-force is a non-standard unit and does not comply with the SI Metric System. == 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. The term Kilopond has been declared obsolete〔European Economic Community, Council Directive of 18 October 1971 on the approximation of the laws of the Member States relating to units of measurement (Directive 71/354/EEC), Annex, Chapter III.〕 and should no longer be used. It is also used for tension of bicycle spokes, for informal references to pressure in kilograms per square centimeter (1 kp/cm2) which is the technical atmosphere (at) and very close to 1 bar and the standard atmosphere (atm), for the draw weight of bows in archery, and to define the "metric horsepower" (PS) as 75 metre-kiloponds per second.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Kilogram-force」の詳細全文を読む スポンサード リンク
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