The movement of objects can be described using motion graphs and numerical values. These are both used to help in the design of faster and more efficient vehicles.

Part of

Distance is how far an object moves. It does not include an associated direction, so distance is a scalar quantity.

Speed is the rate of change of distance - it is the distance travelled per unit time. Like distance, speed does not have an associated direction, so it is a scalar quantity.

When people walk, run, or travel in a car, their speed will change. They may speed up, slow down or pause for traffic. The speed at which a person can walk, run or cycle depends on many factors including:

- age
- terrain
- fitness
- distance travelled

Some typical values for speed in metres per second (m/s) include:

Method of travel | Typical speed (m/s) |
---|---|

walking | 1.5 |

running | 3 |

cycling | 6 |

car | 13-30 |

train | 50 |

aeroplane | 250 |

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

The distance travelled by an object moving at constant speed can be calculated using the equation:

distance travelled = speed × time

This is when:

- distance travelled (
*s*) is measured in metres (m) - speed (
*v*) is measured in metres per second (m/s) - time (
*t*) is measured in seconds (s)

A car travels 500 m in 50 s, then 1,500 m in 75 s. Calculate its average speed for the whole journey.

First calculate total distance travelled (*s*):

500 + 1,500 = 2,000 m

Then calculate total time taken (*t*):

50 + 75 = 125 s

Then rearrange to find *v*: