Key learning points

1. Sometimes speed is measured in different units.
2. Approximately 17 countries (roughly 9%) use mph.
3. When travelling abroad, it is useful to convert speed limits to help judge the speed of the road.

Keywords

• Metric - Metric units are based around the standard units of metre, gram and litre.

• Imperial - Imperial is a system of units for measuring, which was created in the early 1800s during the British Empire.

• Speed - Speed is the rate at which something is moving. It is measured as the distance travelled per unit of time.

• Direct proportion - Two variables are in direct proportion if they have a constant multiplicative relationship.

Common misconception