Kilometres per hour (American spelling: kilometers per hour) is a unit of both speed (scalar) and velocity (vector). The symbol is km·h⁻¹ or km/h but is often, though incorrectly, abbreviated to kph (see also mph). It is often spoken and sometimes written as klicks or kays in slang usage. English language spread in the United States. ... The definition, agreement and practical use of units of measurement have played a crucial role in human endeavour from early ages up to this day. ... Speed is the rate of motion, or equivalently the rate of change of position, many times expressed as distance d moved per unit of time t. ... In physics, a scalar is a simple physical quantity that does not depend on direction, and therefore does not depend on the choice of a coordinate system. ... The velocity of an object is simply its speed in a particular direction. ... In physics and in vector calculus, a spatial vector is a concept characterized by a magnitude, which is a scalar, and a direction (which can be defined in a 3-dimensional space by the Euler angles). ... Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ... Slang is the use of highly informal words and expressions that are not considered standard in the speakers dialect or language. ...

By definition, an object travelling at a speed of 1 km·h⁻¹ in a straight line for an hour would move 1 kilometre. km redirects here. ...

Although much more common in everyday usage than m/s, it is not an SI unit (because the hour isn't). Cover of brochure The International System of Units. ... The hour (symbol: h) is a unit of time. ...

Conversions

• 3.6 km·h⁻¹ ≡ 1 m·s⁻¹, the SI derived unit of speed, metre per second
• 1 km·h⁻¹ ≈ 0.277 78 m·s⁻¹
• 1 km·h⁻¹ ≈ 0.621 37 mph ≈ 0.911 34 feet per second
• 1 knot ≡ 1.852 km·h⁻¹ exactly

The metre, or meter (US), is a measure of length. ... Look up second in Wiktionary, the free dictionary. ... SI derived units are part of the SI system of measurement units and are derived from the seven SI base units. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... The metre, or meter (US), is a measure of length. ... Look up second in Wiktionary, the free dictionary. ... Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ... Feet per second is a unit of speed; it expressses the number of feet traveled in one second. ... A knot is a unit of speed, abbreviated kt or kn. ...

See also

• Orders of magnitude (speed)

To help compare different orders of magnitude, the following list describes various speed levels between 1. ...

External links

• Conversion Calculator for Units of Speed