Editing Base unit of measurement (section)

== Background ==
In the language of [[measurement]], ''[[physical quantities]]'' are [[quantifiable]] aspects of the world, such as [[time]], [[distance]], [[velocity]], [[mass]], [[temperature]], [[energy]], and [[weight]], and ''units'' are used to describe their magnitude or quantity. Many of these quantities are related to each other by various physical laws, and as a result the units of a quantities can be generally be expressed as a product of powers of other units; for example, momentum is mass multiplied by velocity, while velocity is distance divided by time. These relationships are discussed in [[dimensional analysis]]. Those that can be expressed in this fashion in terms of the base units are called [[Derived unit (measurement)|derived units]].