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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 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 temperature, about 4 °C, was not accurately known, but one of the advantages of the new definition was that the precise Celsius value of the temperature was not actually important. [29] [Note 9] The final conclusion was that one cubic decimetre of water at its maximum density was equal to 99.92072% of the mass of the provisional kilogram ...
[6] [7] [8] Quizlet's blog, written mostly by Andrew in the earlier days of the company, claims it had reached 50,000 registered users in 252 days online. [9] In the following two years, Quizlet reached its 1,000,000th registered user. [10] Until 2011, Quizlet shared staff and financial resources with the Collectors Weekly website. [11]
To redefine the value of a kilogram without an artefact the value of the Planck constant must be known to twenty parts per billion. [19] Scientific metrology, through the development of the Kibble balance and the Avogadro project, has produced a value of Planck constant with low enough uncertainty to allow for a redefinition of the kilogram. [18]
"The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10 −34 when expressed in the unit J s , which is equal to kg m 2 s −1 , where the metre and the second are defined in terms of c and ∆ ν Cs ."
Greek masses similarly bear a nominal resemblance to Greek currency yet the origin of the Greek standards of weights is often disputed. [11] There were two dominant standards of weight in the eastern Mediterranean: a standard that originated in Euboea and that was subsequently introduced to Attica by Solon , and also a standard that originated ...
Cambridge Assessment English or Cambridge English develops and produces Cambridge English Qualifications and the International English Language Testing System ().The organisation contributed to the development of the Common European Framework of Reference for Languages (CEFR), the standard used around the world to benchmark language skills, [2] and its qualifications and tests are aligned with ...