International System of Units
- an internationally accepted coherent system of physical units, derived from the MKSA system, using the meter, kilogram, second, ampere, kelvin, mole, and candela as the basic units (SI units) of the fundamental quantities length, mass, time, electric current, temperature, amount of substance, and luminous intensity. Abbr.: SI[trans. of the earlier F name Système Internationale d'Unités]
* * *or Système International d'Unités or SI systemInternational decimal system of weights and measures derived from and extending the metric system of units.Adopted by the 11th General Conference on Weights and Measures in 1960, it was developed to eliminate overlapping but different systems of units of measures fostered by rapid advances in science and technology in the 19th–20th centuries. Its fundamental units include the metre (m) for length, the kilogram (kg) for mass, and the second (sec) for time. Derived units include those for force (newton, N), energy (joule, J), and power (watt, W).
* * *International System of Units (SI) International System of Units (SI)international decimal system of weights and measures derived from and extending the metric system of units. Adopted by the 11th General Conference on Weights and Measures in 1960, it is abbreviated SI in all languages.Rapid advances in science and technology in the 19th and 20th centuries fostered the development of several overlapping systems of units of measurements as scientists improvised to meet the practical needs of their disciplines. The early international system devised to rectify this situation was called the metre-kilogram-second (MKS) system. The General Conference on Weights and Measures added three new units (among others) in 1948: a unit of force (the newton), defined as that force which gives to a mass of one kilogram an acceleration of one metre per second per second; a unit of energy (the joule), defined as the work done when the point of application of a newton is displaced one metre in the direction of the force; and a unit of power (the watt), which is the power that in one second gives rise to energy of one joule. All three units are named for eminent scientists.The 1960 International System builds on the MKS system. Its seven basic units, from which other units are derived, are currently defined as follows: for length, the metre, defined as the distance traveled by light in a vacuum in 1/299,792,458 second; for mass, the kilogram, which equals 1,000 grams as defined by the international prototype kilogram of platinum-iridium in the keeping of the International Bureau of Weights and Measures in Sèvres, France; for time, the second, the duration of 9,192,631,770 periods of radiation associated with a specified transition of the cesium-133 atom; for electric current, the ampere, which is the current that, if maintained in two wires placed one metre apart in a vacuum, would produce a force of 2 × 10−7 newton per metre of length; for luminous intensity, the candela, defined as the intensity in a given direction of a source emitting radiation of frequency 540 × 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian; for amount of substance, the mole, defined as containing as many elementary entities of a substance as there are atoms in 0.012 kg of carbon-12; and for thermodynamic temperature, the kelvin.
* * *
Look at other dictionaries:
International System of Units — n. SI … English World dictionary
International System of Units — SI redirects here. For other uses, see Si (disambiguation). Cover of brochure The International System of Units The International System of Units (abbreviated SI from French: Système international d unités) is the modern … Wikipedia
international system of units — tarptautinė vienetų sistema statusas T sritis fizika atitikmenys: angl. international system of units; SI system vok. internationales Einheitensystem, n; SI System, n rus. международная система единиц, f; система СИ, f pranc. système d’unités… … Fizikos terminų žodynas
International System of Units (SI) — ▪ Table International System of Units (SI) Base units unit abbreviation physical quantity metre m length second s time kilogram kg mass ampere A electric current kelvin K thermodynamic temperature candela cd luminous intensity mole mol amount of… … Universalium
International System of Units — Tarptautinė vienetų sistema statusas T sritis Standartizacija ir metrologija apibrėžtis Suderintoji matavimo vienetų sistema, kurią patvirtino ir rekomendavo Generalinė svarsčių ir matų konferencija (CGPM – Conférence générale des poids et… … Penkiakalbis aiškinamasis metrologijos terminų žodynas
International System of Units — Tarptautinė vienetų sistema statusas T sritis ekologija ir aplinkotyra apibrėžtis Suderintoji matavimo vienetų sistema, kurią patvirtino ir rekomendavo Generalinė svarsčių ir matų konferencija (CGPM – Conférence générale des poids et mesures).… … Ekologijos terminų aiškinamasis žodynas
International System of Units — A system of measurements, based on the metric system, adopted at the 11th General Conference on Weights and Measures of the International Organization for Standardization (1960) to cover both the coherent units (basic, supplementary, and derived… … Medical dictionary
International System of Units — noun a complete metric system of units of measurement for scientists; fundamental quantities are length (meter) and mass (kilogram) and time (second) and electric current (ampere) and temperature (kelvin) and amount of matter (mole) and luminous… … Useful english dictionary
International System of Units — noun Date: 1932 a system of units based on the metric system and developed and refined by international convention especially for scientific work abbreviation SI … New Collegiate Dictionary
international system of units — noun the SI system of units … English new terms dictionary