Convert kilometer/hour to Mach (20°C, 1 atm)

kilometer/hour

Definition: The unit kilometers per hour (symbol: km/h) is a unit of speed expressing the number of kilometers traveled in one hour.

History/origin: The unit of kilometers per hour is based on the meter, which was formally defined in 1799. According to the Oxford English Dictionary, the term kilometer first came into use in 1810. It was not until later in the mid-late 19th century however, that the use of kilometers per hour became more widespread; the myriametre (10,000 meters) per hour was preferred for expressing speed.

Current use: Km/h is currently the most commonly used unit of speed around the world and is typically used for car speeds and road signs. It is also common for both miles per hour as well as kilometers per hour to be displayed on car speedometers. There are many abbreviations for the unit kilometers per hour (kph, kmph, k.p.h, KMph., etc.), but "km/h" is the SI unit symbol.

Mach (20°C, 1 atm)

Definition: Mach (20°C, 1 atm) is a measure of speed or the magnitude of velocity. For conversion purposes, its value is 343.6 times the reference unit, meter/second.