Speed is defined as. The rate of change of position of an object in any direction. Speed is measured as the ratio of distance to the time in which the distance was covered. Speed is a scalar quantity as it has only direction and no magnitude
Two essential measurements to calculating average speed are distance and time.
The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph). For air and marine travel the knot is commonly used.
when total time is very important, e.g. the average speed of train, because we may then calculate time for our journey.
Speed is the time rate at which an object is moving along a path, while velocity is the rate and direction of an object's movement. ... For example, 50 km/hr (31 mph) describes the speed at which a car is traveling along a road, while 50 km/hr west describes the velocity at which it is traveling.
