Running metrics can be confusing. Should you use miles or kilometres? What pace do you need to run to break four hours for the marathon? What speed do you need to run a 5K in under 20 minutes? The ...

It is not only moving objects that have varying speed. The speed of the wind and the speed of sound also vary. A typical value for the wind is about 12 m/s and the speed of sound in air is about 330 m ...