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Density – practice for Years 6–7

Sample questions on Density with the right answer and a worked solution, from easy to hard. In the Pickles Academy app a child gets new questions of the same kind every time, so they can't just learn the answers by heart.

Subject
Physics
Year
Years 6–7
Curriculum area
Matter and objects

Question types: Calculating density

Rule: Density

Density is the mass of 1 m³ of a material: ρ = m ÷ V. So m = ρ × V and V = m ÷ ρ.

Water is 1000 kg/m³ = 1 g/cm³. Anything less dense than water floats on it (ice, wood).

Example: 0.5 m³ of gold (19 300 kg/m³): m = 19 300 × 0.5 = 9650 kg

Watch out: Match the units: g/cm³ × cm³ gives grams, kg/m³ × m³ gives kilograms.

Sample questions

  1. Question 1 Easy

    An object with a volume of 20 cm³ has a mass of 50 g. What is its density in g/cm³?

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    Answer: 2.5 g/cm³

    How it works: ρ = m ÷ V = 50 g ÷ 20 cm³ = 2.5 g/cm³. That is about the density of glass.

  2. Question 2 Normal

    Glass has a density of 2500 kg/m³. What is the mass of 2 m³ of it?

    Show the solution
    Answer: 5000 kg

    How it works: m = ρ × V = 2500 kg/m³ × 2 m³ = 5000 kg.

  3. Question 3 Hard

    An object has a mass of 125 g and a volume of 50 cm³. What is its density in kg/m³?

    Show the solution
    Answer: 2500 kg/m³

    How it works: ρ = 125 g ÷ 50 cm³ = 2.5 g/cm³ = 2500 kg/m³ (1 g/cm³ = 1000 kg/m³). That is about the density of glass.

Related topics

All Physics topics

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