- Unit of length
A unit of length is a way of measuring
length ordistance .Common units of length in the
International System of Units (SI) are:
*metre and its multiples, such as "centimetre " or "kilometre "Non-SI units of length include:
* fermi (fm) (= 1femtometre in SI units)
*angstrom (Å) (= 100picometre s in SI units)
* micron (= 1micrometre in SI units)
*Norwegian/Swedish mil (= 10,000 metres)Common
Imperial unit s andU.S. customary units of length include:
*inch (25.4 mm)
* mil (one thousandth of an inch, one thou)
* foot ( 12 inches, 0.3048 m)
*yard (3 ft, 0.9144 m)
* (terrestrial)mile (5280 ft, 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 inAncient 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 humanhair (around 80 micrometres)
*Abeard-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.ee also
*
Systems of measurement
*Medieval weights and measures
*English unit
*Orders of magnitude (length)
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