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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 ...
It had a mass equal to the mass of 1 dm 3 of water at the temperature of its maximum density, which is approximately 4 °C. [13] 1875–1889: The Metre Convention was signed in 1875, leading to the production of the International Prototype of the Kilogram (IPK) in 1879 and its adoption in 1889. [14]
The international prototype of the kilogram (IPK) is an artifact standard of platinum–iridium alloy that was defined as having a mass of exactly one kilogram. Platinum–iridium alloys are alloys of the platinum group precious metals platinum and iridium. Typical alloy proportions are 90:10 or 70:30 (Pt:Ir).
As with a definition based upon carbon‑12, the Avogadro constant would also have been fixed. The kilogram would then have been defined as "the mass equal to that of precisely 1000 / 196.966 5687 × 6.022 141 79 × 10 23 atoms of gold" (precisely 3 057 443 620 887 933 963 384 315 atoms of gold or about 5.077 003 71 fixed moles).
The international prototype of the kilogram (IPK) is an artefact or prototype that was defined to have a mass of exactly one kilogram.. In metrology (the science of measurement), a standard (or etalon) is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. [1]
Here’s why correctly quantifying mass is more important than you think. Scientists Want to Define the Kilogram by Gravity—Not Electricity. They’re Onto Something.
The base units are defined in terms of the defining constants. For example, the kilogram is defined by taking the Planck constant h to be 6.626 070 15 × 10 −34 J⋅s, giving the expression in terms of the defining constants [1]: 131 1 kg = (299 792 458) 2 / (6.626 070 15 × 10 −34)(9 192 631 770) h Δν Cs / c 2 .
The unit of length was 10 7 m (the hebdometre, nominally the Earth quadrant), the unit of mass was an unnamed unit equal to 10 −11 g and the unit of time was the second. The units of mass and length were scaled incongruously to yield more consistent and usable electric units in terms of mechanical measures.