Speed
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In kinematics, the speed of a moving object is the rate at which the distance travelled by the object changes with time. The average speed of an object in an interval of time is the distance travelled
Speed can be thought of as the rate at which an object covers distance. A fast-moving object has a high speed and covers a relatively large distance in a given amount of time, while a slow-moving object covers a relatively small amount of distance in the same amount of time.
Kilometres per hour
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The kilometre per hour is a unit of speed, expressing the number of kilometres travelled in one hour.
Speed
…additionally the direction of motion. Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s). The kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph), are also used as units of speed. For air and marine travel, the knot is commonly used. The fastest…
A car speedometer that indicates measured speed in kilometres per hour.
Speed limit sign in the Republic of Ireland, using "km/h."