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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").
The SI system after the 2019 definition: Base units as defined in terms of physical constants and other base units. Here, means is used in the definition of . The SI system after 1983, but before the 2019 redefinition: Base unit definitions in terms of other base units (for example, the metre is defined as the distance travelled by light in a specific fraction of a second), with the constants ...
The International Prototype of the Kilogram (referred to by metrologists as the IPK or Le Grand K; sometimes called the ur-kilogram, [1] [2] or urkilogram, [3] particularly by German-language authors writing in English [3] [4]:30 [5]: 64 ) is an object whose mass was used to define the kilogram from 1889, when it replaced the Kilogramme des ...
This new definition of the kilogram proposed to fix the Avogadro constant at precisely 6.022 14 X × 10 23 mol −1 with the kilogram being defined as "the mass equal to that of 1000 / 12 × 6.022 14 X × 10 23 atoms of 12 C".
Scientists want to define the kilogram by gravity—and not just electricity. Here’s why correctly quantifying mass is more important than you think.
New base unit definitions were adopted on 16 November 2018, and they became effective on 20 May 2019. The definitions of the base units have been modified several times since the Metre Convention in 1875, and new additions of base units have occurred. Since the redefinition of the metre in 1960, the kilogram had been the only base unit still ...
kilogram: kg mass "The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram." 3rd CGPM (1901, CR, 70) The mass of one litre of water at the temperature of melting ice. A litre is one thousandth of a cubic metre. M second: s time
The current definitions of the kilogram, ampere, kelvin, and mole be revised; The wording of base unit definitions should change emphasis from explicit unit to explicit constant definitions. The new definitions were adopted at the 26th CGPM on 16 November 2018, and came into effect on 20 May 2019. [41]