Calculate the average speed of a train which covers a distance of 624 km in 13 hours.

Hello!

The average speed of something is defined as the total length of the path travelled divided by the time spent. The sense of this definition is that if a body travel the given path during the given time with the constant speed, this speed would be the same as the average speed.

But this definition allows any instantaneous speed, for example a train can accelerate, then move with some constant speed, then decelerate and finally stay at a station.

In our case, the path is 624 km and the time is 13 hours. The average speed is

624/13 = 48 (km/h).

This speed may be also expressed in other units. For example, one kilometer is 1000 meters and one hour is 3600 seconds, therefore this speed is equal to

48*1000/3600 approx 13.3 (m/s).