International System of Units


Also found in: Dictionary, Thesaurus, Legal, Financial, Encyclopedia, Wikipedia.

International System of Units

 

In·ter·na·tion·al Sys·tem of U·nits (SI),

, Système International d'Unités (in'tĕr-na'shŭn-ăl sis'tem yū'nits, sēs-tĕm' ahn-tĕr-nahs-ē'ōn-nahl' dūn'nē-tā'),
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 units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance, respectively; supplementary units proposed include the radian (rad) for plane angle and steradian (sr) for solid angle; derived units (for example, force, power, frequency) are stated in terms of the basic units (for example, velocity is in meters per second, m s-1). Multiples (prefixes) in descending order are: exa- (E, 1018), peta- (P, 1015), tera- (T, 1012), giga- (G, 109), mega- (M, 106), kilo- (k, 103), hecto- (h, 102), deca- (da, 101), deci- (d, 10-1), centi- (c, 10-2), milli- (m, 10-3), micro- (μ, 10-6), nano- (n, 10-9), pico- (p, 10-12), femto- (f, 10-15), atto- (a, 10-18). Proposed prefixes are zetta- (Z, 1021), yotta- (Y, 1024), zepto- (z, 10-21), and yocto- (y, 10-24).
[Fr. Système International d'Unités]

International System of Units (SI)

an internationally accepted scientific system of expressing length, mass, and time in base units (IU) of meters, kilograms, and seconds, replacing the old centimeter-gram-second system. The SI system includes as standard measurements the ampere, candle, Kelvin scale, and mole.

In·ter·na·tion·al Sys·tem of U·nits

(SI) (in'tĕr-nash'ŭn-ăl sis'tĕm yū'nits)
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 units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), Kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance; supplementary units proposed include the radian (rad) for plane angle and steradian (sr) for solid angle; derived units (e.g., force, power, frequency) are stated in terms of the basic units (e.g., velocity is in meters per second, m/sec-1). Multiples (prefixes) in descending order are: exa- (E, 1018), peta- (P, 1015), tera- (T, 1012), giga- (G, 109), mega- (M, 106), kilo- (k, 103), hecto- (h, 102), deca- (da, 101), deci- (d, 10-1), centi- (c, 10-2), milli- (m, 10-3), micro- (μ, 10-6), nano- (n, 10-9), pico- (p, 10-12), femto- (f, 10-15), and atto- (a, 10-18). The prefix zepto (z) has been proposed for 10-21.
[Fr. Système International d'Unités]

International System of Units

; Système International d'Unités; SI units system of weights and measures, e.g. metre (m; length); kilogram (kg; mass); litre (L; volume); second (s; time); ampere (A; electric current); kelvin (K; temperature); pascal (Pa; pressure); mole (mol; amount of substance); derived units (e.g. force, power, frequency) are stated in terms of the basic units; multiples of units are termed, in descending order: tera- (T; 1012), giga- (G; 109), mega- (M, 106), kilo- (K; 103), hecto- (h; 102), deca (da; 101), deci- (d; 10-1), centi- (c, 10-2), milli- (m, 10-3), micro- (μ, 10-6), nano- (n, 10-9)

In·ter·na·tion·al Sys·tem of U·nits

(SI) (in'tĕr-nash'ŭn-ăl sis'tĕm yū'nits)
System of measurements, based on the metric, to cover both coherent units (basic, supplementary, and derived units) and the decimal multiples and submultiples of these units formed by use of prefixes proposed for general international scientific and technologic use. SI proposes seven basic units: meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), candela (cd), and mole (mol) for the basic quantities of length, mass, time, electric current, temperature, luminous intensity, and amount of substance, respectively. Multiples (prefixes) in descending order are: exa- (E, 1018), peta- (P, 1015), tera- (T, 1012), giga- (G, 109), mega- (M, 106), kilo- (k, 103), hecto- (h, 102), deca- (da, 101), deci- (d, 10-1), centi- (c, 10-2), milli- (m, 10-3), micro- (μ, 10-6), nano- (n, 10-9), pico- (p, 10-12), femto- (f, 10-15), atto- (a, 10-18). Proposed prefixes are zetta- (Z, 1021), yotta- (Y, 1024), zepto- (z, 10-21), and yocto- (y, 10-24).
[Fr. Système International d'Unités]

International System of Units

References in periodicals archive ?
In presenting the standards, both the International System of Units and customary units have been employed.
Since the development of the International System of Units (SI), many experiments have been developed in order to realize SI units to ever lower levels of uncertainty.
Mass stands out as the last physical parameter of the International System of Units that still rests on a specific artifact.
Over the last three months we have seen some positive developments such as the extension of the property visa period from six months to three years and the implementation of the International System of Units, which will bring uniformity of scale to the market, Elaine Jones, CEO, Asteco Property Management, said in a statement.
A quick reference guide to the International System of Units (SI) is found at the back of the volume.
A new paper from a NIST researcher describes the essential physics of SET devices, discusses various schemes for making capacitance and current standards based on SET devices, and covers the relevance of SET standards for fundamental constants and the International System of Units.

Medical browser ?
Full browser ?