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Combination Units

Combination Units

Owned by Shira Nagel
Last updated: Feb 20, 2016

Unit symbols obtained by multiplication or division

Multiplication

 

Symbols for derived units formed by multiplication are joined with a centre dot (•) or a non-breaking space.

For example:

  • N•m or N m

In English, when unit names are combined to denote multiplication of the units concerned, they are separated with a hyphen or a space.

For example:

  • newton-metre or newton metre

The plural is formed by converting the last unit name to the plural form.
For example:

  • ten newton-metres

 

 

Division

Division is indicated by a horizontal line, by a solidus (oblique stroke, /) or by negative exponents.

For example:

  • The "metre per second" can be written m/s, m s−1, or m•s−1

Only one solidus should be used.
For example:

  • kg/(m•s2) and kg•m−1•s−2 are acceptable, but kg/m/s2 is ambiguous and unacceptable

Unacceptability of unit symbols and unit names used together

Unit symbols and unit names are not used together.
For example:

  • C/kg, C • kg-1, or coulomb per kilogram

But not:

  • coulomb/kg; coulomb per kg; C/kilogram; coulomb • kg-1; C per kg; coulomb/kilogram



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