Density is defined as:

The mass per unit volume of a material

Objects made from low density materials typically have a low mass

Similarly sized objects made from high density materials have a high mass

• For example, a bag full of feathers is far lighter compared to a similar bag full of metal

• Or another example, a balloon is less dense than a small bar of lead despite occupying a larger volume

Density Equation :

Gases, for examples, are less dense than solids because the molecules are more spread out (same mass, over a larger volume)

The units of density depend on what units are used for mass and volume:

• If the mass is measured in g and volume in cm3, then the density will be in g/cm3

• If the mass is measured in kg and volume in m3, then the density will be in kg/m3

• This table gives some examples of densities on common materials

  • If a material is more dense than water (1000 kg/m3), then it will sink