Units of measure - EdexcelPressure

Pressure indicates the amount of force being exerted per unit area.

The units for pressure can be quite complex depending on whether you are working in imperial or metric units. Scientists might use Pascals as the unit for pressure but in GCSE Maths it is likely that compound units will be used. For example, the air pressure of a basketball is about 8 pounds per square inch. Other compound units that might be used are kg/m² or g/cm². Sometimes you might even see N/m², which means Newtons per square metre.

Notice how all the compound units have one thing in common: they are all per square inch or /m² or /cm². All are saying “per unit area” and so the calculation will always involve dividing by the area.

Example

The surface area of a pair of skis is 0.25 m². A skier has a mass of 70 kg. How much pressure, in kg/m², does the skier exert on the snow?

The units are telling us to divide the number of kg by the number of m².

The pressure is 280 kg/m².