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The International System of Units (abbreviated SI from the French language name Système international d'unités) is the modern form of the There was an error working with the wiki: Code[43]. It is the world's most widely used There was an error working with the wiki: Code[44], both in everyday There was an error working with the wiki: Code[45] and in There was an error working with the wiki: Code[46]. English units are still used in some scientific applications, but note also that parsecs in astronomy, calories and mmHg in the medical sciences, and electronvolts in physics are not part of the specific system of units known as SI, to just scratch the surface.

The older metric system included several groupings of units. The SI was developed in 1960 from the There was an error working with the wiki: Code[8] (cgs) system which, in turn, had many variants.

The SI introduced several newly named units. The SI is not static it is a living set of standards where units are created and definitions are modified with international agreement as measurement technology progresses.

With few exceptions, the system is used in every country in the world, and many countries do not maintain official definitions of other units. There was an error working with the wiki: Code[9], industrial use of SI is increasing, but popular use is still limited. In the There was an error working with the wiki: Code[10] is official policy but not yet complete. Those countries that still recognize non-SI units (e.g. the U.S. and UK) have redefined their traditional non-SI units There was an error working with the wiki: Code[11].

History

:See main articles: There was an error working with the wiki: Code[12].

The There was an error working with the wiki: Code[13]) which had been commissioned by king There was an error working with the wiki: Code[14]".

A month after the There was an error working with the wiki: Code[15]) on There was an error working with the wiki: Code[16] a number of variations have evolved and their use spread around the world replacing many traditional There was an error working with the wiki: Code[17].

By the end of There was an error working with the wiki: Code[18] and There was an error working with the wiki: Code[19] systems. It was recognised that additional steps were needed to There was an error working with the wiki: Code[20]. As a result the 9th There was an error working with the wiki: Code[47] (CGPM), in 1948, asked the There was an error working with the wiki: Code[48] (CIPM) to conduct an international study of the measurement needs of the scientific, technical, and educational communities.

Based on the findings of this study, the 10th CGPM in 1954 decided that an international system should be derived from six base units to provide for the measurement of temperature and optical radiation in addition to mechanical and electromagnetic quantities. The six base units recommended were the There was an error working with the wiki: Code[21], was added in 1970 by the 14th CGPM.

Units

The international system of units consists of a set of units together with a set of There was an error working with the wiki: Code[22]es. The units of SI can be divided into two subsets. There are the seven SI base unit. Each of these base units are nominally dimensionally independent. From these seven base units several SI derived unit are derived. In addition to the SI units there are also a set of There was an error working with the wiki: Code[49].

{|align=center style="margin:1em auto 1em auto background: #f9f9f9 border: 1px #aaaaaa solid border-collapse: collapse"

! colspan="3" |SI base units

|-

|Name

|Symbol

|Quantity

|-

|Metre

|m

|There was an error working with the wiki: Code[50]

|-

|There was an error working with the wiki: Code[51]

|kg

|Mass

|-

|There was an error working with the wiki: Code[52]

|s

|There was an error working with the wiki: Code[53]

|-

|Ampere

|A

|Current (electricity)

|-

|There was an error working with the wiki: Code[54]

|K

|There was an error working with the wiki: Code[55]

|-

|There was an error working with the wiki: Code[23]

|mol

|There was an error working with the wiki: Code[56]

|-

|There was an error working with the wiki: Code[57]

|cd

|There was an error working with the wiki: Code[58]

|-

|}

A There was an error working with the wiki: Code[24] may be added to units to produce a multiple of the original unit. All multiples are integer powers of ten. For example, kilo- denotes a multiple of a thousand and milli- denotes a multiple of a thousandth hence there are one thousand millimetres to the metre and one thousand metres to the kilometre. The prefixes are never combined: a millionth of a kilogram is a milligram not a microkilogram.

{| style="margin:1em auto 1em auto background: #f9f9f9 border: 1px #aaaaaa solid border-collapse: collapse"

! colspan="11" align=center|There was an error working with the wiki: Code[1]

|-- align="center"

! Name

| There was an error working with the wiki: Code[2]

| There was an error working with the wiki: Code[3]

| There was an error working with the wiki: Code[4]

| There was an error working with the wiki: Code[5]

| There was an error working with the wiki: Code[6]

| There was an error working with the wiki: Code[7]

| There was an error working with the wiki: Code[8]

| There was an error working with the wiki: Code[9]

| There was an error working with the wiki: Code[10]

| There was an error working with the wiki: Code[11]

|-- align="center"

! Symbol

| Y

| Z

| E

| P

| T

| G

| M

| k

| h

| da

|--

! Factor

| 1024

| 1021

| 1018

| 1015

| 1012

| 109

| 106

| 103

| 102

| 101

|-- align="center" style="border-top: 2px solid #000 "

! Name

| There was an error working with the wiki: Code[12]

| There was an error working with the wiki: Code[13]

| There was an error working with the wiki: Code[14]

| There was an error working with the wiki: Code[15]

| There was an error working with the wiki: Code[16]

| There was an error working with the wiki: Code[17]

| There was an error working with the wiki: Code[18]

| There was an error working with the wiki: Code[19]

| There was an error working with the wiki: Code[20]

| There was an error working with the wiki: Code[21]

|-- align="center"

! Symbol

| d

| c

| m

| µ

| n

| p

| f

| a

| z

| y

|--

! Factor

| 10-1

| 10-2

| 10-3

| 10-6

| 10-9

| 10-12

| 10-15

| 10-18

| 10-21

| 10-24

|}

Base units

The international system (SI) of units defines seven SI base units: There was an error working with the wiki: Code[59]s defined by an There was an error working with the wiki: Code[60]. All other physical units can be derived from these base units: these are known as SI derived units. Derivation is by There was an error working with the wiki: Code[61]. Use There was an error working with the wiki: Code[62]es to abbreviate long numbers. The following are the base units from which all others are derived. They are dimensionally independent, with the exception of the Metre and There was an error working with the wiki: Code[63]. The candela was formerly a There was an error working with the wiki: Code[64] but has been redefined in terms of the other SI base units. The metre also was a fundamental unit, but has since been redefined in terms of the second. They are still considered "base units" for historical reasons, but are in fact dependent on the other units for their definition.

{| style="margin:1em auto 1em auto background: #f9f9f9 border: 1px #aaaaaa solid border-collapse: collapse"

|+ style="font-size:largerfont-weight:bold"|SI base units

!Name

!Symbol

!Measure

!Definition

!Historical&nbspOrigin/Justification

|-

|Metre or meter

| style="text-align: center" | m

|There was an error working with the wiki: Code[10]

|The unit of length is equal to the length of the path travelled by There was an error working with the wiki: Code[11] in a There was an error working with the wiki: Code[12] during the time interval of 1/299 792 458 of a second. Defined by: 17th CGPM (1983) Resolution 1, CR 97

|1/10&nbsp000&nbsp000 of the distance from the There was an error working with the wiki: Code[13]'s equator to the North Pole measured through There was an error working with the wiki: Code[14].

|-

|There was an error working with the wiki: Code[15]

| style="text-align: center" | kg

|Mass

|The unit of mass is equal to the mass of the international prototype kilogram (a There was an error working with the wiki: Code[1]. See the There was an error working with the wiki: Code[16] article for an alternative definition.

|The mass of one There was an error working with the wiki: Code[2]" and symbolized G. The There was an error working with the wiki: Code[3] is defined as a derived unit, equal to 1/1000 of a kilogram prefixes such as mega are applied to the gram, not the kg e.g. Gg, not Mkg. It is also the only unit still defined by a physical prototype instead of a measurable natural phenomenon.

|-

|There was an error working with the wiki: Code[17]

| style="text-align: center" | s

|There was an error working with the wiki: Code[18]

|The unit of time is the duration of exactly 9 192 631 770 periods of the There was an error working with the wiki: Code[19] corresponding to the transition between two There was an error working with the wiki: Code[20]s of the There was an error working with the wiki: Code[21] of the There was an error working with the wiki: Code[22]-133 atom at a temperature of 0 K. Defined by: 13th CGPM (1967-1968) Resolution 1, CR 103

|1/86400 of the There was an error working with the wiki: Code[23]

|-

|Ampere

| style="text-align: center" | A

|Current (electricity)

|The unit of electrical current is the constant current which, if maintained in two straight parallel There was an error working with the wiki: Code[4]s, of infinite length and negligible cross-section, placed 1 metre apart in a vacuum, would produce a force between these conductors equal to 2&times10 &minus7 There was an error working with the wiki: Code[24]s per metre of length. Defined by: 9th CGPM (1948) Resolution 7, CR 70

|-

|There was an error working with the wiki: Code[25]

| style="text-align: center" | K

|Temperature

|The unit of thermodynamic temperature (or absolute temperature) is the fraction 1/273.16 (exactly) of the thermodynamic temperature at the There was an error working with the wiki: Code[5]. Defined by: 13th CGPM (1967) Resolution 4, CR 104

|1/100 of the difference between the boiling and freezing points of water

|-

|There was an error working with the wiki: Code[6]

| style="text-align: center" | mol

|quantity of There was an error working with the wiki: Code[26] (mass/mass)

|A mole is the quantity of substance that contains the same number of elementary entities (There was an error working with the wiki: Code[7], depending on the substance) as there are atoms in 0.012 kilograms of pure There was an error working with the wiki: Code[8] (NA) is approximately equal to 6.02214199&times1023. Defined by: 14th CGPM (1971) Resolution 3, CR 78

|one gram per There was an error working with the wiki: Code[27]

|-

|There was an error working with the wiki: Code[28]

| style="text-align: center" | cd

|There was an error working with the wiki: Code[29]

|The unit of luminous intensity is the luminous intensity, in a given direction, of a source that emits There was an error working with the wiki: Code[9] There was an error working with the wiki: Code[30] of frequency 540&times1012 There was an error working with the wiki: Code[31] and that has a radiant intensity in that direction of 1/683 Watt per There was an error working with the wiki: Code[32]. Defined by: 16th CGPM (1979) Resolution 3, CR 100

|the There was an error working with the wiki: Code[33]

|-

|}

SI derived units are part of the There was an error working with the wiki: Code[25]s and are derived from the seven SI base units.

Dimensionless derived units

The following SI units are actually dimensionless ratios, formed by dividing two identical SI units. They are therefore considered by the There was an error working with the wiki: Code[26] to be derived. Formally, their SI unit is simply the number 1, but they are given these special names, for use whenever the lack of a unit might be confusing.

{| style="margin:1em auto 1em auto background: #f9f9f9 border: 1px #aaaaaa solid border-collapse: collapse"

|+ style="font-size:largerfont-weight:bold"|Dimensionless SI units

!Name

!Symbol

!Quantity

!Definition

|-

| There was an error working with the wiki: Code[2]

| rad

| There was an error working with the wiki: Code[3]

| The unit of angle is the angle subtended at the centre of a circle by an arc of the circumference equal in length to the radius of the circle. There are 2\pi radians in a circle.

|-

| There was an error working with the wiki: Code[4]

| sr

| There was an error working with the wiki: Code[1]

| The unit of solid angle is the 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. There are 4\pi steradians on a sphere.

|}

Derived units with special names

Base units can be put together to derive units of measurement for other quantities. Some have been given names.

{| style="margin:1em auto 1em auto background: #f9f9f9 border: 1px #aaaaaa solid border-collapse: collapse"

|+ style="font-size:largerfont-weight:bold"|Named units derived from SI base units

|-

! Name

! There was an error working with the wiki: Code[17]

! There was an error working with the wiki: Code[3]

! Expression in terms of other units

! Expression in terms of SI base units

|-

| There was an error working with the wiki: Code[18]

| Hz

| Frequency

| 1/s

| s?1

|-

| There was an error working with the wiki: Code[19]

| N

| Force, There was an error working with the wiki: Code[20]

| m?kg/s2

| m?kg?s?2

|-

| There was an error working with the wiki: Code[21]

| J

| There was an error working with the wiki: Code[4], Heat

| N?m

| m2?kg?s?2

|-

| Watt

| W

| Power (physics), There was an error working with the wiki: Code[22]

| J/s

| m2?kg?s?3

|-

| There was an error working with the wiki: Code[5]

| Pa

| There was an error working with the wiki: Code[6]

| N/m2

| m?1?kg?s?2

|-

| There was an error working with the wiki: Code[7]

| lm

| There was an error working with the wiki: Code[23]

| cd?sr

| cd

|-

| There was an error working with the wiki: Code[24]

| lx

| There was an error working with the wiki: Code[25]

| lm/m2

| m?2?cd

|-

| There was an error working with the wiki: Code[26]

| C

| Electric charge or There was an error working with the wiki: Code[27]

| s?A

| s?A

|-

| Volt

| V

| There was an error working with the wiki: Code[8], There was an error working with the wiki: Code[28]

| W/A&nbsp=&nbspJ/C

| m2?kg?s?3?A?1

|-

| There was an error working with the wiki: Code[9]

| ?

| There was an error working with the wiki: Code[10], There was an error working with the wiki: Code[29]

| V/A

| m2?kg?s?3?A?2

|-

| There was an error working with the wiki: Code[30]

| F

| There was an error working with the wiki: Code[31]

| C/V

| m&minus2?kg?1?s4?A2

|-

| There was an error working with the wiki: Code[11]

| Wb

| There was an error working with the wiki: Code[32]

| J/A

| m2?kg?s?2?A?1

|-

| There was an error working with the wiki: Code[12]

| T

| There was an error working with the wiki: Code[33], There was an error working with the wiki: Code[34]

| V?s/m2&nbsp=&nbspWb/m2

| kg?s?2?A?1

|-

| There was an error working with the wiki: Code[13]

| H

| There was an error working with the wiki: Code[35]

| V?s/A&nbsp=&nbspWb/A

| m2?kg?s?2?A?2

|-

| There was an error working with the wiki: Code[14]

| S

| There was an error working with the wiki: Code[36]

| 1/?

| m?2?kg?1?s3?A2

|-

| There was an error working with the wiki: Code[37]

| Bq

| There was an error working with the wiki: Code[38] (decays per unit time)

| 1/s

| s?1

|-

| There was an error working with the wiki: Code[15]

| Gy

| There was an error working with the wiki: Code[39] (of There was an error working with the wiki: Code[40])

| J/kg

| m2?s?2

|-

| There was an error working with the wiki: Code[41]

| Sv

| There was an error working with the wiki: Code[42] (of ionizing radiation)

| J/kg

| m2?s?2

|-

| There was an error working with the wiki: Code[43]

| kat

| There was an error working with the wiki: Code[44]

| mol/s

| s?1?mol

|-

| There was an error working with the wiki: Code[16]

| °C

| There was an error working with the wiki: Code[45]

| colspan="2" | T°C&nbsp=&nbspTK&nbsp?&nbsp273.15

|-

| colspan="5" class="noprint" style="text-align: right font-size: smaller" | [There was an error working with the wiki: Code[1]There was an error working with the wiki: Code[2] edit]

|}

Other quantities and units

{| style="margin:1em auto 1em auto background: #f9f9f9 border: 1px #aaaaaa solid border-collapse: collapse"

! colspan="5" | Compound units derived from SI units

|-

|Name

|Symbol

|Quantity

|Expression in terms of SI base units

|-

| There was an error working with the wiki: Code[5] || m2

| There was an error working with the wiki: Code[6] || m2

|-

| There was an error working with the wiki: Code[7] || m3

| There was an error working with the wiki: Code[8] || m3

|-

| There was an error working with the wiki: Code[9] || m·s&minus1

| There was an error working with the wiki: Code[10], Velocity || m·s&minus1

|-

| There was an error working with the wiki: Code[11] || m·s&minus2

| There was an error working with the wiki: Code[12] || m·s&minus2

|-

| metre per second cubed || m·s&minus3

| There was an error working with the wiki: Code[13] || m·s&minus3

|-

| radian per second || rad·s&minus1

| There was an error working with the wiki: Code[14] || s&minus1

|-

| newton second || N·s

| There was an error working with the wiki: Code[15], There was an error working with the wiki: Code[16] ||| kg·m·s&minus1

|-

| newton metre second || N·m·s

| There was an error working with the wiki: Code[17] || kg·m2·s&minus1

|-

| newton metre || N·m

| Torque || kg·m2·s&minus2

|-

| reciprocal metre || m&minus1

| There was an error working with the wiki: Code[18] || m&minus1

|-

| There was an error working with the wiki: Code[19] || kg·m&minus3

| There was an error working with the wiki: Code[20], mass density || kg·m&minus3

|-

| cubic metre per kilogram || kg&minus1·m3

| specific volume || kg&minus1·m3

|-

| mole per cubic metre || m&minus3·mol

| amount (-of-substance) concentration || m&minus3·mol

|-

| cubic metre per mole || m3·mol&minus1

| molar volume || m3·mol&minus1

|-

| joule per kelvin || J·K&minus1

| There was an error working with the wiki: Code[21], Entropy || kg·m2·s&minus2·K&minus1

|-

| joule per kelvin mole || J·K&minus1·mol&minus1

| molar heat capacity, molar entropy

| kg·m2·s&minus2·K&minus1·mol&minus1

|-

| joule per kilogram kelvin

| J·K&minus1·kg&minus1

| There was an error working with the wiki: Code[22], specific entropy

| m2·s&minus2·K&minus1

|-

| joule per mole || J·mol&minus1

| molar energy || kg·m2·s&minus2·mol&minus1

|-

| joule per kilogram || J·kg&minus1

| specific energy || m2·s&minus2

|-

| joule per cubic metre || J·m&minus3

| energy density || kg·m&minus1·s&minus2

|-

| newton per metre || N·m&minus1 = J·m&minus2

| There was an error working with the wiki: Code[23] || kg·s&minus2

|-

| watt per square metre || W·m&minus2

| heat flux density, irradiance || kg·s&minus3

|-

| watt per metre kelvin

| W·m&minus1·K&minus1

| There was an error working with the wiki: Code[24]

| kg·m·s&minus3·K&minus1

|-

| There was an error working with the wiki: Code[25]

| m2·s&minus1

| kinematic There was an error working with the wiki: Code[26], There was an error working with the wiki: Code[27] coefficient

| m2·s&minus1

|-

| There was an error working with the wiki: Code[28]

| Pa·s = N·s·m&minus2

| dynamic There was an error working with the wiki: Code[29] || kg·m&minus1·s&minus1

|-

| coulomb per cubic metre

| C·m&minus3

| electric charge density || m&minus3·s·A

|-

| ampere per square metre || A·m&minus2

| electric current density || A·m&minus2

|-

| siemens per metre || S·m&minus1

| There was an error working with the wiki: Code[3]

| kg&minus1·m&minus3·s3·A2

|-

| siemens square metre per mole

| S·m2·mol&minus1

| molar conductivity || kg-1·s3·mol&minus1·A2

|-

| farad per metre || F·m&minus1

| There was an error working with the wiki: Code[30] || kg&minus1·m&minus3·s4·A2

|-

| henry per metre || H·m&minus1

| There was an error working with the wiki: Code[4] || kg·m·s&minus2·A&minus2

|-

| volt per metre

| V·m&minus1

| Electric field strength || kg·m·s&minus3·A&minus1

|-

| ampere per metre || A·m&minus1

| Magnetic field strength || A·m&minus1

|-

| candela per square metre || cd·m&minus2

| There was an error working with the wiki: Code[31] || cd·m&minus2

|-

| coulomb per kilogram || C·kg&minus1

| exposure (X and gamma rays) || kg&minus1·s·A

|-

| gray per second || Gy·s&minus1

| absorbed dose rate || m2·s&minus3

|-

! colspan="5" style="text-align: right font-size: smaller" class="noprint" | [There was an error working with the wiki: Code[1]There was an error working with the wiki: Code[2] edit]

|}

SI writing style

Symbols are written in There was an error working with the wiki: Code[27] itself is written "There was an error working with the wiki: Code[28]".

The one exception is the There was an error working with the wiki: Code[29] in There was an error working with the wiki: Code[30].

Abbreviated symbols, unlike spelt-out full names of units, should not be pluralised—for example "25&nbspkg", not "25&nbspkgs"—though they sometimes are. For spelt-out unit names in English, all are made plural by adding an 's', except There was an error working with the wiki: Code[65], There was an error working with the wiki: Code[66], and There was an error working with the wiki: Code[67], all of which are the same in singular and plural.<

Symbols do not have an appended period/full stop (.) unless at the end of a sentence.

It is preferable to write symbols in upright Roman type (m for metres, L for litres), so as to differentiate from the There was an error working with the wiki: Code[68] used for mathematical variables (m for mass, l for length).

A space should separate the number and the symbol, e.g. "2.21&nbspkg", "7.3There was an error working with the wiki: Code[2]&nbspm2", "22&nbsp°C" http://physics.nist.gov/Pubs/SP811/sec07.html. Exceptions are the symbols for plane angular degrees, minutes and seconds (°,&nbsp?&nbspand&nbsp?), which are placed immediately after the number with no intervening space.

Spaces may be used to group decimal digits in threes, e.g. 1&nbsp000&nbsp000 or 342&nbsp142 (in contrast to the commas or dots used in other systems, e.g. 1,000,000 or 1.000.000). This is presumably to reduce confusion because a comma is used as a decimal in some countries (such as France). In print, the space used for this purpose is typically narrower than that between words.

The 10th resolution of There was an error working with the wiki: Code[31] in 2003 declared that "the symbol for the There was an error working with the wiki: Code[32] shall be either the There was an error working with the wiki: Code[33] on the line or the There was an error working with the wiki: Code[69] on the line". In practice, the decimal point is used in English, and the comma in most other European languages.

Symbols for derived units formed from multiple units by multiplication are joined with a space or centre dot (·), e.g. N m or N·m.

Symbols formed by division of two units are joined with a There was an error working with the wiki: Code[34] (/), or given as a negative There was an error working with the wiki: Code[70]. For example, the "metre per second" can be written "m/s", "m&nbsps&minus1", "m·s&minus1" or \fracThere was an error working with the wiki: Code[3]There was an error working with the wiki: Code[4]. A solidus should not be used if the result is ambiguous, i.e. "kg·m&minus1·s&minus2" is preferable to "kg/m·s2". (Taylor (page 13) specifically calls for the use of a solidus. Many computer users will type the / character provided on American computer keyboards, which in turn produces the Unicode character U+002F, which is named solidus. Taylor does not offer suggestions about which mark should be used when more sophisticated typesetting options are available.)

In countries using ideographic writing systems such as Chinese and Japanese, often the full symbol for the unit, including prefixes, is placed in one square. (See the "Letterlike Symbols" Unicode subrange)

Spelling variations

Several nations, notably the United States, typically use the spellings 'meter' and 'liter' instead of 'metre' and 'litre' in keeping with standard There was an error working with the wiki: Code[71] spelling. In addition, the official US spelling for the There was an error working with the wiki: Code[72] 'deca' is 'deka'.http://physics.nist.gov/cuu/Units/prefixes.html

The unit 'ampere' is often shortened to 'amp' (singular) or 'amps' (plural).

Conversion factors

The relationship between the units used in different systems is determined by convention or from the basic definition of the units. Conversion of units from one system to another is accomplished by use of a There was an error working with the wiki: Code[35]. There are several compilations of conversion factors see, for example Appendix B of NIST SP 811.

Cultural Issues

The worldwide adoption of the metric system as a tool of economy and everyday commerce was based to some extent on the lack of customary systems in many countries to adequately describe some concepts, or as a result of an attempt to standardize the many regional variations in the customary system. International factors also affected the adoption of the metric system, as many countries increased their trade. Scientifically, it provides ease when dealing with very large and small quantities because it lines up so well with our There was an error working with the wiki: Code[73] There was an error working with the wiki: Code[74].

There are many units in everyday and scientific use that are not derived from the seven SI base units — metre, kilogram, second, ampere, Kelvin, mole and candela — combined with the SI prefixes. In some cases these deviations have been approved by the BIPM.http://www.bipm.org/en/si/si_brochure/chapter4/table8.html Examples include:

the many units of time—minute(min), hour(h), day, week, month, year, century—in use besides the SI second.

the There was an error working with the wiki: Code[75] temperature scale Kelvin is never employed in everyday use

electric energy is often billed in Watt-hour instead of megajoules

use of kilometre per hour (km/h) instead of the SI metre per second for automotive speed fuel usage is often given in litres per 100 km (L/100km).

the There was an error working with the wiki: Code[36] (nautical mile per hour) used to measure travel distance and speed of ships and aircraft (1 nautical mile = 1852 m ? 1 minute of latitude).

astronomical distances measured in There was an error working with the wiki: Code[76]s, There was an error working with the wiki: Code[77]s and There was an error working with the wiki: Code[78]s instead of, say, petametres (a light year is about 9.461 Pm or about 9 461 000 000 000 000 m)

atomic scale units used in physics and chemistry, such at the There was an error working with the wiki: Code[37]

some There was an error working with the wiki: Code[38] (CGS) units

In some countries, the informal There was an error working with the wiki: Code[39] measurement has become 250&nbspml, and prices for items are sometimes given per 100&nbspg rather than per kilogram

In the U.S., blood glucose measurements are recorded in milligrams per decilitre (mg/dl) in Europe, the standard is millimole/litre (mmol/l).

The fine-tuning that has happened to the metric base unit definitions over the past 200 years, as experts have tried periodically to find more precise and reproducible methods, does not affect the everyday use of metric units. Since most non-SI units in common use, such as the There was an error working with the wiki: Code[79], are nowadays defined in terms of SI units, any change in the definition of the SI units results in a change of the definition of the older units as well.

Trade

The There was an error working with the wiki: Code[80] has a directive banning non-SI markings after There was an error working with the wiki: Code[81] There was an error working with the wiki: Code[82] on any goods imported into the European Union. This applies to all markings on products, enclosed directions and papers, packaging, and advertisements.

Related

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There was an error working with the wiki: Code[87]es - used to quantify large amounts of computer There was an error working with the wiki: Code[88]

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Other There was an error working with the wiki: Code[102]:

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References and external articles

Official

BIPM Bureau International des Poids et Mesures (SI maintenance agency) (home page)

BIPM brochure (SI reference)

ISO 1000:1992 SI units and recommendations for the use of their multiples and of certain other units

ISO 31/1000/80000

NIST Official Publications

NIST Special Pub 814: Interpretation of the SI for the United States and Federal Government Metric Conversion Policy

Weights and Measures Act, Canada

IEEE/ASTM SI 10-2002 Standard for Use of the International System of Units (SI): The Modern Metric System (ANSI approved, joint IEEE/ASTM standard)

Rules for SAE Use of SI (Metric) Units

Information

US NIST reference on SI

chart

SI - Its history and use in science and industry

A Dictionary of Units of Measurement

Cyrillic transcription of SI symbols

Judson, Lewis B., Weights and Measures Standards of the United States: A brief history, There was an error working with the wiki: Code[42] Special Publication 447, orig. iss. October 1963, updated March 1976 (46 page PDF file)

Metric system and conversion tables (courtesy French property advice)

metre-info - an encyclopaedia of all metric units

Online metric conversions

Online metric conversions Conversion factors based on the Guide for the Use of the International System of Units, B. N. Taylor, NIST, 1995

There was an error working with the wiki: Code[1], Wikipedia: The Free Encyclopedia. Wikimedia Foundation.

Council Directive 80/181/EEC of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC, as amended with Directive 89/617/EEC (which changed the cutoff date in article 3.2 to There was an error working with the wiki: Code[109] There was an error working with the wiki: Code[110]) and Directive 1999/103/EC (which further changed the date to There was an error working with the wiki: Code[109] There was an error working with the wiki: Code[112]).

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BIPM

NPL - Kilogram

NIST -SI

Pro-metric pressure groups

The UK Metric Association

The US Metric Association

On Metre: Metric in Canada

Canadian Metric Association

Pro-customary measures pressure groups

The British Weights and Measures Association

Proposed adjustment to the International system

Dimensional Analysis of the current SI system - Blaze Labs Research

Further reading

I. Mills, Tomislav Cvitas, Klaus Homann, Nikola Kallay, IUPAC: Quantities, Units and Symbols in Physical Chemistry, 2nd ed., Blackwell Science Inc 1993, ISBN 0-632-03583-8.

See also

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