Two cubes, Cube P and Cube Q, are made from different materials. Cube P has a mass of 540 g and a volume of 200 cm³. Cube Q has the same volume as Cube P but a mass of 1600 g. State what is meant by the term density and explain which cube is made from the denser material, justifying your answer.

Cambridge International IGCSE Physics (0625) — 1.4 Density · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Density is the mass per unit volume of a material.
Cube Q is denser.
Both cubes have the same volume, so the one with the greater mass has the greater density.
Cube Q has a greater mass (1600 g vs 540 g) for the same volume, so its density is greater.

Examiner tips

  • Use the definition of density first, then compare masses because volumes are equal.
  • Show the comparison clearly – state the volumes are equal and the mass of Q is larger.
  • Use the word ‘denser’ to answer the question directly.

Common mistakes

  • Saying ‘Cube P is denser’ – the masses are reversed.
  • Failing to mention that the volumes are equal before comparing masses.
  • Using the wrong units or omitting the word ‘per unit volume’ in the definition.

Mark scheme (4 marks)

  1. Density is the mass per unit volume (of a material/object)
  2. Cube Q is denser / Cube Q has the greater density
  3. Both cubes have the same volume, so the one with the greater mass has the greater density
  4. Cube Q has a greater mass (1600 g compared to 540 g) for the same volume, so its density is greater

Key terms in this question

density · mass · volume

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