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The Metre Convention was signed on 20 May 1875 and further formalised the metric system (a predecessor to the SI), quickly leading to the production of the IPK.The IPK is one of three cylinders made in London in 1879 by Johnson Matthey, which continued to manufacture nearly all of the national prototypes as needed until the new definition of the kilogram came into effect in 2019.
Prior to the redefinition, the kilogram and several other SI units based on the kilogram were defined by an artificial metal object called the international prototype of the kilogram (IPK). [1] There was broad agreement that the older definition of the kilogram should be replaced.
The kilogram (also spelled kilogramme [1]) is the base unit of mass in the International System of Units (SI), having the unit symbol kg. [1] The word "kilogram" is formed from the combination of the metric prefix kilo-(meaning one thousand) and gram; [2] it is colloquially shortened to "kilo" (plural "kilos").
As the IPK is the definitive kilogram, there is no way of telling whether the IPK had been losing mass or the national prototypes had been gaining mass. [89] During the course of the century, the various national prototypes of the kilogram were recalibrated against the international prototype of the kilogram (IPK) and, therefore, against each ...
After the metre was redefined in 1960, the International Prototype of the Kilogram (IPK) was the only physical artefact upon which base units (directly the kilogram and indirectly the ampere, mole and candela) depended for their definition, making these units subject to periodic comparisons of national standard kilograms with the IPK. [38]
The law also replaced the three names gravet, grave and bar by a single generic unit name: the gram. [12] The new gram was equal to the old gravet. Four new prefixes (deca, hecto, kilo, and myria) were added to the metric system to cover almost the same range of units as in 1793 (milligram, centigram, decigram, gram, decagram, hectogram ...
A Law Reference Collection, 2011, ISBN 1624680003 and ISBN 978-1-62468-000-7; Trinxet, Salvador. Trinxet Reverse Dictionary of Legal Abbreviations and Acronyms, 2011, ISBN 1624680011 and ISBN 978-1-62468-001-4. Raistrick, Donald. Index to Legal Citations and Abbreviations. 3rd ed. London: Sweet & Maxwell, 2008. This book focuses more on British ...
Prior to 2019, the definition of the kilogram was based on a physical object known as the International Prototype of the Kilogram (IPK). After considering alternatives , in 2013 the General Conference on Weights and Measures (CGPM) agreed on accuracy criteria for replacing this definition with one based on the use of a Kibble balance.