UNIT OF LENGTH

A 'unit of length' is a way of measuring length or distance.
Common units of length in the International System of Units (SI) are:

★ metre (or "metre" in British English) and its multiples, such as "centimetre" or "kilometre"
Non-SI units of length include:

★ fermi (fm) (= 1 femtometre in SI units)

★ angstrom (Å) (= 100 picometres in SI units)

★ micron (= 1 micrometre in SI units)

★ Norwegian/Swedish mil (= 10,000 metres)
Common Imperial units and U.S. customary units of length include:

★ inch (25.4 mm)

★ foot (0.3048 m)

★ yard (0.9144 m)

★ (terrestrial) mile (1609.344 m)
In addition, the following are used by mariners:

★ fathom (for depth) (1.8288 m)

★ nautical mile (1852 m)
Surveyors in the United States continue to use:

★ chain (~20.1m)

★ rod (also called pole or perch) (~5 m)
Horse racing keeps alive:

★ furlong (~201 m)
Astronomical measure uses:

★ astronomical unit (AU) (~149 gigametres)

★ light year (ly) (~9.46 petametres)

★ parsec (pc) (~30.8 petametres), including kiloparsec (kpc) and megaparsec (Mpc)
Physics also uses:

★ Planck length

★ Bohr radius
Archaic units of distance are described in the article on Ancient weights and measures. They include:

★ cana

★ cubit

★ league

★ li (China)

★ pace (the "double pace" of about 5 feet used in Ancient Rome)

★ verst (Russia)
In everyday conversation, and in informal literature, it is common to see lengths measured in units of objects of which everyone knows the approximate width. Common examples are:

★ Football field (generally around 110 metres, depending on the country)

★ Widths of a human hair (around 80 micrometres)

★ A beard-second is a unit created as a teaching concept. It is the distance that a beard grows in a second (about 5 nanometres)

★ Smoot, a jocular unit of length created as part of an MIT fraternity prank.

Contents

See also

See also

★ Systems of measurement

★ Medieval weights and measures

★ English unit