Kilometre

Template:Short description Template:Redirect Template:Use dmy dates Template:Use British English Template:Infobox unit

The kilometre (SI symbol: km; Template:IPAc-en or Template:IPAc-en), spelt kilometer in American and Philippine English, is a unit of length in the International System of Units (SI), equal to one thousand metres (kilo- being the SI prefix for Template:Val). It is the preferred measurement unit to express distances between geographical places on land in most of the world; notable exceptions are the United States and the United Kingdom where the statute mile is used.

PronunciationEdit

Template:More citations needed section There are two common pronunciations for the word.<ref>Template:Citation</ref>

The first pronunciation follows a pattern in English whereby SI units are pronounced with the stress on the first syllable (as in kilogram, kilojoule and kilohertz) and the pronunciation of the actual base unit does not change irrespective of the prefix (as in centimetre, millimetre, nanometre and so on). It is generally preferred by the British Broadcasting Corporation (BBC), the Canadian Broadcasting Corporation (CBC), and the Australian Broadcasting Corporation (ABC).Template:Citation needed

Many other users, particularly in countries where SI (the metric system) is not widely used, use the second pronunciation with stress on the second syllable.<ref>Template:Cite news</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The second pronunciation follows the stress pattern used for the names of measuring instruments (such as micrometer, barometer, thermometer, tachometer, and speedometer). The contrast is even more obvious in countries that use the American spelling of the word metre. This pronunciation is irregular because it makes the kilometre the only SI unit with the stress on the second syllable.

After Australia introduced the metric system in 1970, the first pronunciation was declared official by the government's Metric Conversion Board. However, the Australian prime minister at the time, Gough Whitlam, insisted that the second pronunciation was the correct one because of the Greek origins of the two parts of the word.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Equivalence to other units of lengthEdit

1 kilometre	≡	Template:Val	metres
	≈	Template:Val	feet
	≈	Template:Val	yards
	≈	0.621	miles
	≈	0.540	nautical miles
	≈	Template:Val	astronomical units Template:Efn
	≈	Template:Val	light-years Template:Efn
	≈	Template:Val	parsecs

HistoryEdit

File:Division of the meridien.PNG

Historical divisions of the meridian in France

By a decree of 8 May 1790, the French National Constituent Assembly ordered the French Academy of Sciences to develop a new measurement system. In August 1793, the French National Convention decreed the metre as the sole length measurement system in the French Republic and it was based on Template:Sfrac millionth of the distance from the orbital poles (either North or South) to the Equator, this being a truly internationally based unit. The first name of the kilometre was "Millaire". Although the metre was formally defined in 1799, the myriametre (Template:Val metres) was preferred to the "kilometre" for everyday use. The term "myriamètre" appeared a number of times in the text of Develey's book Physique d'Emile: ou, Principes de la science de la nature,<ref>Template:Cite book</ref> (published in 1802), while the term kilometre only appeared in an appendix. French maps published in 1835 had scales showing myriametres and "lieues de PosteTemplate:-" (Postal leagues of about Template:Val metres).<ref>Template:Cite map</ref>

The Dutch, on the other hand, adopted the kilometre in 1817 but gave it the local name of the mijl.<ref>Template:Cite book</ref> It was only in 1867 that the term "kilometerTemplate:-" became the only official unit of measure in the Netherlands to represent Template:Val metres.<ref>Template:Cite news</ref>

Two German textbooks dated 1842<ref name=Europa1842>{{#invoke:citation/CS1|citation |CitationClass=web }} Text version of Malaisé's book.</ref><ref>Template:Cite book</ref> and 1848<ref>Template:Cite book</ref> respectively give a snapshot of the use of the kilometre across Europe: the kilometre was in use in the Netherlands and in Italy, and the myriametre was in use in France.

In 1935, the International Committee for Weights and Measures (CIPM) officially abolished the prefix "myria-" and with it the "myriametre", leaving the kilometre as the recognised unit of length for measurements of that magnitude.<ref>Template:Cite book</ref>

The symbol km for the kilometre is in lower case and has been standardised by the BIPM.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> A slang term for the kilometre in the US, UK, and Canadian militaries is klick.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Kilometre recordsEdit

Some sporting disciplines feature Template:Val (one-kilometre) races in major events (such as the Olympic Games). In some disciplines—although world records are catalogued—one-kilometre events remain a minority.

1 km world records for various sporting disciplines
Discipline	Name	Time (min:sec)	Location	Date	Comments
Running (M)	Noah Ngeny	2:11.96<ref>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>	Rieti, Italy	Template:Dts	Not an Olympic event
Running (F)	Svetlana Masterkova	2:28.98<ref>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>	Brussels	Template:Dts	Not an Olympic event
Speed skating (M)	Pavel Kulizhnikov	1:05.69	Salt Lake City	Template:Dts
Speed skating (F)	Brittany Bowe	1:11.61	Salt Lake City	Template:Dts
Track cycling (M)	François Pervis	56.303<ref>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>	Aguascalientes, Mexico	Template:Dts	No official Template:Val women's record