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SI base unit

From Academic Kids

The SI system of units defines seven SI base units: fundamental physical units defined by an operational definition.

All other physical units can be derived from these base units: these are known as SI derived units. Derivation is by dimensional analysis. Use SI prefixes to abbreviate long numbers.

Template:SI base units

No circular references

Note that there are two base units above which do not appear to be defined purely in terms of other base units.

  1. The ampere is defined in terms of newtons. However, one newton is 1 kg · m · s-2.
  2. The candela is defined in terms of hertz, watt and steradians. One hertz is 1 s-1, one watt is 1 J · s-1 = 1 kg · m2 · s-3 and the steradian is the dimensionless solid angle subtended at the centre of a sphere of radius r by a portion of the surface of the sphere having an area r2.

Therefore there are no circular references in the definition of the base units.

See also

External links

da:Grundlggende SI-enheder el:Διεθνές Σύστημα Μονάδων es:Unidades bsicas del SI et:SI-ssteemi_hikud eo:Mezurunuo fr:Units de base du systme international hr:SI osnovne jedinice is:SI hu:SI alapegysg nl:SI basiseenheid no:SI enhetene simple:SI base unit sl:Osnovne enote SI sr:СИ основне јединице fi:SI-perusyksikt sv:SI-enhet zh-cn:国际标准基准单位 zh-tw:國際標準基準單位

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