0580

Compound Measures

Number

Density

  • Density is mass divided by volume, usually in g/cm³ or kg/m³
  • Where the object is a solid shape, its volume may have to be calculated first
The same triangle layout for density, with mass across the top and density and volume side by side underneath, so mass over volume gives density, mass over density gives volume, and density times volume gives mass
Source: Speed, density & pressure by Save My Exams

Pressure

  • Pressure is force divided by area, usually in newtons per square metre (N/m²), also called pascals
  • Weight is a force and is not the same quantity as mass
To findCalculate
Densitymass ÷ volume
Massdensity × volume
Volumemass ÷ density
Worked example

Finding a density

A metal block has a mass of 468 g and a volume of 60 cm³. Find its density.

Solution:

  • Density is mass divided by volume
  • 468 ÷ 60 = 7.8
  • The units follow the division: grams divided by cubic centimetres
  • The density is 7.8 g/cm³