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.

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 in 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 velocity of an object is its speed in a particular direction. Velocity is a vector quantity because it has both a magnitude and an associated direction. To calculate velocity, displacement is used in calculations, rather than distance.

Unlike distance, which is a scalar quantity, displacement is a vector quantity. It includes:

- the distance travelled, measured in a straight line from start to finish
- the direction of the straight line