Metre per second
Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector quantity which specifies both magnitude and a specific direction), defined by distance in metres divided by time in seconds.
The SI unit symbols are m·s−1, m s−1, m/s, or m. Where metres per second are several orders of magnitude too slow to be convenient, such as in astronomical measurements, velocities may be given in kilometres per second, where 1 km/s is 1000 metres per second.
1 m/s is equivalent to:
- = 3.6 km·h−1 (exactly)
- ≈ 3.2808 feet per second (approximately)
- ≈ 2.2369 miles per hour (approximately)
- ≈ 1.9438 knots (approximately)
1 foot per second = 0.3048 m·s−1 (exactly)
1 mile per hour = 0.44704 m·s−1 (exactly)
1 km·h−1 = 0.27 m·s−1 (exactly)
1 kilometre per second is equivalent to:
- ≈ 0.6213 miles per second (approximately)
- ≈ 2237 miles per hour (approximately)
Relation to other measures 
Although m·s−1 is an SI derived unit, it could be viewed as more fundamental than the metre, since the metre is now derived from the speed of light in vacuum, which is defined as exactly 299 792 458 m·s−1 by the BIPM. One metre per second is 1/299 792 458 of the speed of light in vacuum.
The benz, named in honor of Karl Benz, has been proposed as an equivalent to the metre per second. Although it has seen some support as a practical unit, primarily from German sources, it was refuted as the SI unit of velocity and has not seen widespread use or acceptance.
See also 
- SI brochure, Section 5.1
- BIPM - metre
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