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metres per second: 299 792 458: Approximate values (to three significant digits) kilometres per hour: 1 080 000 000: miles per second: 186 000: miles per hour [1] 671 000 000: astronomical units per day: 173 [Note 1] parsecs per year: 0.307 [Note 2] Approximate light signal travel times; Distance: Time: one foot: 1.0 ns: one metre: 3.3 ns: from ...
kilometre per hour: km/h km/h US spelling: kilometer per hour: 1.0 km/h (0.62 mph) km/h mph; Imperial & US customary: mile per hour: mph mph 1.0 mph (1.6 km/h) mph km/h; mile per second: mi/s mi/s 1.0 mi/s (1.6 km/s) mi/s km/s; foot per second: ft/s (foot/s) ft/s long code "foot/s" outputs foot per second (and never feet) 1.0 ft/s (0.30 m/s) ft ...
Abbreviations for "kilometres per hour" did not appear in the English language until the late nineteenth century. The kilometre, a unit of length, first appeared in English in 1810, [9] and the compound unit of speed "kilometers per hour" was in use in the US by 1866. [10] "Kilometres per hour" did not begin to be abbreviated in print until ...
For example, 10 miles per hour can be converted to metres per second by using a sequence of conversion factors as shown below: = . Each conversion factor is chosen based on the relationship between one of the original units and one of the desired units (or some intermediary unit), before being rearranged to create a factor that cancels out the ...
The record is 44.72 km/h (27.78 mph), measured between meter 60 and meter 80 of the 100 meters sprint at the 2009 World Championships in Athletics by Usain Bolt. [4] [5] (Bolt's average speed over the course of this race was 37.578 km/h or 23.35 mph.) [6] Compared to quadrupedal animals, humans are exceptionally capable of endurance, but incapable of great speed. [7]
The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph). For air and marine travel, the knot is commonly used.
Since the velocity of propagation is very high – about 300,000 kilometers per second – the wave of an alternating or oscillating current, even of high frequency, is of considerable length. At 60 cycles per second, the wavelength is 5,000 kilometers, and even at 100,000 hertz, the wavelength is 3 kilometers.
Speed limits are generally indicated on a traffic sign reflecting the maximum permitted speed, expressed as kilometres per hour (km/h) or miles per hour (mph) or both. Speed limits are commonly set by the legislative bodies of national or provincial governments and enforced by national or regional police and judicial authorities.