Unit 22 Section 5 : Density
If you were to fill boxes of the same capacity with different materials you would
find some easier to lift than others. For example, a box of sand would be much
heavier than a box of polystyrene beads. We say that sand is more dense than
polystyrene. Density, mass and volume are connected by these relationships:
Different materials have different densities.
For example, mercury has a density of 13600 kg/m³ and air has a density of 1.4 kg/m³.
An important density to remember is the density of water: it is 1000 kg/m³ or 1 g/cm³.
Practice Questions
Work out the answers to each of these questions then click
to see whether you are correct.
Practice Question 1
Calculate the mass in kilograms of 3 litres of water (remember the density of water is 1 g/cm³).
If you have the density in g/cm³ you need the the volume in cm³ and you can work out the mass in grams.
(a) What is the volume in cm³?
(b) What is the mass in grams? (use mass = density × volume)
(c) What is the mass in kilograms?
Practice Question 2
The metal block shown below has mass 2kg.
Calculate the density of the metal in g/cm³.
If you want the density in g/cm³ you need the mass in grams and the volume in cm³.
(a) What is the mass in grams?
(b) What is the volume in cm³?
(c) What is the density in g/cm³?
Practice Question 3
A type of wood has density 0.7 grams/cm³.
A piece of this wood is 3 cm by 10 cm by 180 cm.
What is the mass of this piece of wood in grams?
If you want the mass in grams, you need the density in g/cm³ and the volume in cm³.
(a) What is the volume in cm³?
(b) Which formula is needed to calculate the mass?
(c) What is the mass in grams?
