Kilometres per hour
The kilometre per hour (American English: kilometer per hour) is a unit of speed, expressing the number of kilometres travelled in one hour. The unit symbol is km/h or km·h−1.
Worldwide, the km/h is the most commonly used speed unit on road signs and car speedometers. Along with the kilowatt hour, km/h is the most commonly used metric unit based on the hour, although the "hour", while not an SI unit, is accepted for use with the International System of Units by the International Bureau of Weights and Measures (BIPM).[2]
In Australian and North American slang and military usage, km/h is commonly pronounced, and sometimes even written, as klicks or kays (K's), although these may also be used to refer to kilometres.[citation needed]
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[edit] Use of kph
The colloquial abbreviations "kph" and "kmph" are sometimes also used in English-speaking countries, in analogy to "miles per hour" (mph), even though the official recommendation from the BIPM is to use "km/h". The symbol (as opposed to abbreviation) is in near-universal use elsewhere, even though the letters "km" and "h" do not always correspond to "kilometres" or "hours" in the language concerned.
The following are translations of the text "kilometres per hour" where either "km" or "h" do not appear in the text.[3]
- Bulgarian Километър в час
- Dutch: kilometer per uur
- German: Kilometer pro Stunde (colloquial more common Stundenkilometer)
- Greek: χιλιόμετρα ανά ώρα / χιλιόμετρα την ώρα
- Italian: Chilometri all'ora
- Polish: kilometr na godzinę
- Portuguese: quilómetros por hora / quilômetro por hora
- Romanian:Kilometri pe oră
- Russian: Километр в час
- Norway: " Kilometer i timen"
- Ukrainian: Кілометр на годину
In all cases, EU directives require the use of "km/h" in official documents in these languages.[4] Similarly, US law requires the use of either "km/h" or "KM/H", but not "KPH" on speedometers.[5]
[edit] Conversions
- 3.6 km/h ≡ 1 m/s, the SI unit of speed, metre per second
- 1 km/h ≈ 0.277 78 m/s
- 1 km/h ≈ 0.621 37 mph ≈ 0.911 34 feet per second
- 1 knot ≡ 1.852 km/h (exactly)
- 1 mile per hour ≡ 1.609344 km/h (~1.61 km/h)[6]
| m/s | km/h | mph | knot | ft/s | |
|---|---|---|---|---|---|
| 1 m/s = | 1 | 3.6 | 2.236936 | 1.943844 | 3.280840 |
| 1 km/h = | 0.277778 | 1 | 0.621371 | 0.539957 | 0.911344 |
| 1 mph = | 0.44704 | 1.609344 | 1 | 0.868976 | 1.466667 |
| 1 knot = | 0.514444 | 1.852 | 1.150779 | 1 | 1.687810 |
| 1 ft/s = | 0.3048 | 1.09728 | 0.681818 | 0.592484 | 1 |
(Values in bold face are exact.)
[edit] See also
[edit] References
- ^ Canadian DX model accessdate = 2011-08-04}}
- ^ BIPM brochure (SI reference)
- ^ "Online Translation- Offering hundreds of dictionaries and translation in more than 800 language pairs". Babylon. http://translation.babylon.com/. Retrieved 2011-01-24.
- ^ The Council of the European Communities (2009-05-27). "Council Directive 80/181/EEC of 20 December 1979 on the approximation of the laws of the Member States relating to Unit of measurement and on the repeal of Directive 71/354/EEC". http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1980L0181:20090527:EN:PDF. Retrieved 2009-09-14.
- ^ "101--Technical Correction--Speedometer Display". 49 CFR Part 571, [Docket No. NHTSA-00-7144], RIN 2127-AG55, Federal Motor Vehicle Safety Standards;. Department of Transport - National Highway Traffic Safety Administration. http://www.mail-archive.com/usma@colostate.edu/msg13801.html. Retrieved 2011-04-18.
- ^ 1 yard ≡ 0.9144 m and
1 mile = 1760 yards thus
1 mile = 1760 × 0.9144 ÷ 1000 km
