The total length of the bar represents both the total distance and the total time taken. The bar is divided into parts. Each part represents the speed as a distance per unit of time. The number of ...

Professor Brian Cox gives an introduction to speed. He defines what is meant by speed and how to calculate speed by applying the ‘distance divided by time’ equation.

The fastest possible speed of sound — 22.4 miles per second, nearly twice its speed in air at the Earth's surface — has been calculated for the first time. British researchers found that such speeds ...