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Kilometers per hour explained

Kilometers per hour is a unit of speed that denotes the number of kilometers traveled in one hour. Widely used in countries that adopt the metric system, it serves as a standard measure for expressing velocities in various contexts, particularly in transportation.

Symbol

The symbol for kilometers per hour is km/h. While "kph" and "kmph" are also used, "km/h" is the internationally recognized and preferred notation.

Applications

The km/h unit is prevalent in several fields:

  • Transportation: Used to measure vehicle speeds and set speed limits on roads and highways.
  • Sports: Applied in tracking the speed of athletes, such as runners and cyclists.
  • Meteorology: Utilized to report wind speeds and monitor weather conditions.

Origin

The term "kilometer" first appeared in English in 1810. Although the meter was formally defined in 1799, the usage of "kilometers per hour" became more prevalent later, especially with the adoption of the metric system in various countries. The unit provided a standardized means to express speed, aligning with the metric measurements of distance and time.

FAQs

Why is meters per second the SI unit for speed instead of kilometers per hour?

In the SI system, the base units for length and time are the meter and the second, respectively. Speed is defined as the distance traveled divided by the time taken, leading to the derived unit of meters per second for speed.

Is km/h used in aviation and maritime contexts?

No, aviation and maritime industries typically use knots to measure speed, as it corresponds with nautical miles, which are more relevant to navigation over long distances.

Are there any instruments specifically designed to measure speed in km/h?

Yes, speedometers in vehicles are calibrated to display speed in km/h, especially in countries using the metric system.

How do I convert kilometers per hour to other speed units?

Use the links below for easy conversions from kilometers per hour to other speed units available on this website.