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The millimetre (SI symbol: mm) is a unit of length in the metric system equal to 10 −3 metres ( 1 / 1 000 m = 0.001 m). To help compare different orders of magnitude , this section lists lengths between 10 −3 m and 10 −2 m (1 mm and 1 cm).
In the SI, base units are the simple measurements for time, length, mass, temperature, amount of substance, electric current and light intensity. Derived units are constructed from the base units, for example, the watt, i.e. the unit for power, is defined from the base units as m 2 ·kg·s −3.
Metrology is a wide reaching field, but can be summarized through three basic activities: the definition of internationally accepted units of measurement, the realisation of these units of measurement in practice, and the application of chains of traceability (linking measurements to reference standards).
The SI comprises a coherent system of units of measurement starting with seven base units, which are the second (symbol s, the unit of time), metre (m, length), kilogram (kg, mass), ampere (A, electric current), kelvin (K, thermodynamic temperature), mole (mol, amount of substance), and candela (cd, luminous intensity). The system can ...
The cubit is an ancient unit of length based on ... These cubit rods range from 523.5 to 529.2 mm (20 + 5 ⁄ 8 ... A History and Measurement Commentary", Journal of ...
The UK statute chain is 22 yards, which is 66 feet (20.1168 m). This unit is a statute measure in the United Kingdom, defined in the Weights and Measures Act 1985. [6] One link is a hundredth part of a chain, which is 7.92 inches (20.1168 cm).
Planck units modified so that 8 π G = 1 are known as reduced Planck units, because the Planck mass is divided by √ 8 π. Also, the Bekenstein–Hawking formula for the entropy of a black hole simplifies to S BH = ( m BH ) 2 /2 = 2 π A BH .
A variety of units of measurement were used in the various independent Italian states and Italian dependencies of foreign empires up to the unification of Italy in the 19th century. The units to measure length, volume, mass, etc., could differ widely between countries or between towns in a country (e.g. Rome and Ancona), but usually not between ...