Kilometre
The kilometre, spelt kilometer in American English, is a unit of length in the metric system, equal to one thousand metres. It is now the measurement unit used 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 unit used.
The abbreviations k or K are commonly used to represent kilometre, but are not recommended by the BIPM. A slang term for the kilometre in the US and UK militaries is .
Pronunciation
There are two common pronunciations for the word.The former follows a 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 irrespective of the prefix. It is generally preferred by the British Broadcasting Corporation and the Australian Broadcasting Corporation.
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. The latter pronunciation follows the stress pattern used for the names of measuring instruments. The contrast is even more obvious in countries using the Commonwealth spelling 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.
Equivalence to other units of length
History
By a decree of 8 May 1790, the 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. The first name of the kilometre was "Millaire".Although the metre was formally defined in 1799, the myriametre 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,, while the term kilometre only appeared in an appendix. French maps published in 1835 had scales showing myriametres and "lieues de Poste".
The Dutch, on the other hand, adopted the kilometre in 1817 but gave it the local name of the mijl. It was only in 1867 that the term "kilometer" became the only official unit of measure in the Netherlands to represent metres.
Two German textbooks dated 1842 and 1848 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 officially abolished the prefix "myria-" and with it the "myriametre", leaving the kilometre as the recognised unit of length for measurements of that magnitude.
Kilometre records
Some sporting disciplines feature races in major events. In some disciplines—although world records are catalogued—one-kilometre events remain a minority.Kilometre world records :
| Discipline | Name | Time | Location | Date | Comments |
| Running | Noah Ngeny | 2:11.96 | Rieti, Italy | Not an Olympic event | |
| Running | Svetlana Masterkova | 2:28.98 | Brussels | Not an Olympic event | |
| Speed Skating | Shani Davis | 1:06.42 | Salt Lake City | ||
| Speed Skating | Cindy Klassen | 1:13.11 | Calgary | ||
| Cycling | Arnaud Tourant | 58.875 | La Paz, Bolivia | No official women's record |