| kilometre
|
| Unit system: |
SI
|
| Unit of... |
length
|
| Symbol: |
km
|
| Unit conversions
|
| 1 km in... |
is equal to...
|
| m |
1000
|
| mm |
106
|
| mi |
0.62137
|
| ft |
3280.8
|
The kilometre (International spelling as used by the International Bureau of Weights and Measures; SI symbol: km) or kilometer (American spelling) is a unit of length in the metric system, equal to one thousand metres (kilo- being the SI prefix for 1000). It is now the measurement unit used officially for expressing 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 the official unit used.
k (pronounced kay) is occasionally used in some English-speaking countries as an alternative for the word kilometre in everyday colloquialised writing and speech.[1][2][3] A slang term for the kilometre in the U.S. military is klick.[4]
Pronunciation
There are two common pronunciations for the word:
The former pronunciation follows the general pattern in English whereby metric units are pronounced with the stress on the first syllable, and the pronunciation of the actual base unit does not change irresepective of the prefix. It is generally preferred by the British Broadcasting Corporation (BBC) and the Australian Broadcasting Corporation (ABC).
Many scientists and other users, particularly in countries where the metric system is not widely used, use the pronunciation with stress on the second syllable.[5][6] The latter pronunciation follows the stress pattern used for the names of measuring instruments (such as micrometer, barometer, thermometer, tachometer and speedometer). The problem with this reasoning, however, is that the word meter in those usages refers to a measuring device, not a unit of length. The contrast is even more obvious in countries using the English rather than American spelling of the word metre.
When Australia introduced the metric system in 1975, 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.[7]
Equivalence to other units of length
History
Although the metre was formally defined in 1799, the myriametre (10,000 metres) was preferred to the "kilometre" for everyday use. The term "myriametré" appeared a number of times in the text of Develey’s book Physique d'Emile: ou, Principes de la science de la nature,[10] (published in 1802), while the term kilometre only appeared in an appendix. French maps published in 1835 had scales showing myriametres and "lieues de Poste" (Postal leagues of about 4288 metres)[11]
The Dutch on the other hand adopted the kilometre in 1817 but gave it the local name of the mijl.[12] It was only in 1867 that the term "kilometer" became the only official unit of measure in the Netherlands to represent 1000 metres.[13]
Two German textbooks dated 1842[14][15] and 1848[16] 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.[17]
Visualisation
The kilometre may be visualised in terms of prominent landmarks.
Niagara Falls
The Mall, London
Kowloon – Hong Kong Crossing
Central Park, Manhattan, New York City
Central Park in New York City is 849 metres wide. It extends (roughly east and west) from Fifth Avenue to Eighth Avenue (also known as Central Park West). The distance between Eighth Avenue and Madison Avenue (one block east of Fifth Avenue) is 1011 metres. The width of the park is visible from many nearby skyscrapers and is walked daily by many people. It is approximately 4 kilometres in length (from north to south).
Error creating thumbnail: Invalid thumbnail parameters or image file with more than 12.5 million pixels
The width of Central Park is visible from many buildings in Manhattan, and the park is walked regularly by many residents and visitors.
Suspension bridges
International usage
The United Kingdom and the United States are the only two developed countries which continue to use miles on road signs.[19]
United Kingdom
In the United Kingdom, road signs show distances in miles[20][21] and location marker posts that are used for reference purposes by road engineers and emergency services show distance references in unspecified units which are kilometre-based.[22]
The advent of the mobile phone has been instrumental in the British Department for Transport authorising the use of driver location signs to convey the distance reference information of location marker posts to road users should they need to contact the emergency services.
United States
In the US, the Metrication in the United States.)
Covering one kilometre
The time taken to cover a kilometre is dependent on one's speed. Walking on flat ground, a hiker can expect to cover one kilometre in 12 minutes[25]
while a car travelling at a speed of 120 kilometres per hour (75 mph)—the speed limit on numerous European expressways—will cover a kilometre in 30 seconds.
Some sporting disciplines feature 1000 m (one-kilometre) races in major events (such as the Olympic Games), but in other disciplines, even though world records are catalogued, the one kilometre event remains a minority event. The world records for various sporting disciplines are:
See also
Notes and references
Listen to this article (
info/dl)
This audio file was created from a revision of the "
Kilometre" article dated 2013-06-27, and does not reflect subsequent edits to the article. (
Audio help)
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.