Miles per hour

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Automobile speedometer, indicating speed in miles per hour on the outer scale and kilometres per hour on the inner scale

Miles per hour (abbreviated mph, MPH or mi/h) is an imperial and United States customary unit of speed expressing the number of statute miles covered in one hour. Although kilometres per hour is now used worldwide, miles per hour remains the standard unit for speed limits in the United States, the United Kingdom, Antigua & Barbuda and Puerto Rico, although the latter two use kilometres for distances.

Roadway usage

These include roads in the United Kingdom,[1] the United States,[2] and UK and US territories; American Samoa,[3] the Bahamas,[4] Belize,[5] British Virgin Islands,[6] the Cayman Islands,[7] Dominica,[8] the Falkland Islands,[9] Grenada,[10] Guam,[11] Burma,[12] The N. Mariana Islands,[13] Samoa,[14] St. Lucia,[15] St. Vincent & The Grenadines,[16] St. Helena,[17] St. Kitts & Nevis,[18] Turks & Caicos Islands,[19] the U.S. Virgin Islands,[20][21] Antigua & Barbuda (although km are used for distance), and Puerto Rico (same as former).

United States road sign with maximum speed noted in standard Mph

Miles per hour are also used in the Canadian rail system.[22] In some countries it may be used to express the speed of delivery of a ball in sporting events such as cricket, tennis and baseball.

Road traffic speeds in other countries are quoted in kilometres per hour. Occasionally, however, both systems are used: for example, in Ireland, a judge considered a speeding case by examining speeds in both kilometres per hour and miles per hour. The judge was quoted as saying the speed seemed "very excessive" at 180 km/h but did not look "as bad" at 112 mph; a reduced fine was still imposed on the speeding driver.[23]

Nautical and aeronautical usage

Nautical and aeronautical applications, however, favour the knot as a common unit of speed: one knot is one nautical mile per hour.

Conversions

1 mph = 0.44704 m/s (exactly)
= 1.609344 km/h (exactly)
≈ 1.467 ft/s (approximately)
0.868976 kn
Conversions between common units of speed
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.)

1 Mph = 0.000277778 Mps (Miles Per Second)

Example: Apollo 11 attained speeds of 25,000 Mph, which converts to about 7 Mps. If Apollo 11 were to travel at 25,000 Mph from New York to Los Angeles it would reach Los Angeles in under 6 minutes.

See also

References

  1. Speed limits (UK) Department for Transport. Retrieved 4 August 2015
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  5. http://amandala.com.bz/news/?p=263765&upm_export=pdf
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