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kilopond

Convert between kiloponds and other major units of force.

A unit of force, 1939 – late 20ᵗʰ century, the Central European and Scandinavian equivalent of the kilogram-force, the force exerted by a mass of 1 kilogram at the standardized value of the acceleration due to Earth's gravity, 9.80665 meters per second per second; in other words, roughly the weight of a kilogram, 9.80665 newtons. Symbol, kp. Thus instead of a meter–kilogram-force–second system, they had a meter-kilopond-second system. The French equivalent is the kilopoid.

The kilogram had been used in the 19ᵗʰ and early 20ᵗʰ centuries both as a unit of mass and as a unit of weight, which is a force. Distinguishing between the two in favor of mass created the need for a unit of force. In 1934, for example, the Swedish Royal Mint ended the uncertainty in Sweden by declaring the kilogram to be a unit of mass (see source note 1).

The word “kilopond” was used internally by the Physikalisch-Technische Reichanstalt, the official German standards laboratory, as early as 1939. In 1945 Sweden adopted the kilopond as its unit of force. The Verein Deutscher Ingenieure (Society of German Engineers, VDI), however, objected in 1950 to the term's adoption in Germany on the grounds that units ought not to be adopted on a national basis and that “pond” was too close to “pound.” The decision by Technical Committee 12 of the International Standards Organization to recommend adoption of both the kilopond and kilogram-force as synonyms (1955, 1957) removed the first of these objections, and in August 1958 the VDI recommended provisionally that “kilopond” be used for the unit of force.¹

In 1971, the European Economic Community directed that use of this unit cease by 31 December 1977.²

1. G. Ruppel.
Germany's approach to reconciling system usages.
in Systems of Units. National and International Aspects.
Carl F. Kayan, editor.
Publication No. 57 of the AAAS.
Washington, D. C.: American Association for the Advancement of Science, 1959.

Page 238.

2. 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.

sources

The Royal Mint in Sweden enacted a law in 1934 making the kilogram the unit of mass. Then a new unit of force had to be found. It could not be called the kilogram. After some discussions, in 1945 the kilopond was adopted (following the French pattern which has the kilopoid) as the designation for kilogram (force), when the acceleration has the normal value (9.80665 m/s²) at 45° latitude.

The mks system is not related to this kilopond (kp). Unfortunately, the two are often supposed to be related, and this misconception has reacted unfavorably to the mks system. The kilopond system should not exist; it is a half-measure that makes an intricate matter still more intricate.

Matts Bäckström.
The clear MKS system. Contra the obscure old technical unit system.
in Carl F. Kayan, editor.
Systems of Units. National and International Aspects.
Publication No. 57 of the AAAS.
Washington, D. C.: American Association for the Advancement of Science, 1959.
Page 227.