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AQA · GCSE · Physics · Higher

Ring Mass from Density

Q07.5 4 marks

The student determined that the density of the ring was 21 500 kg/m³.

The volume of the ring was 0.44 cm³.

density = mass / volume, ρ=mV\rho=\frac{m}{V}

Calculate the mass of the ring.

Use the Physics Equations Sheet.

Give your answer in kg.

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Marking points

  1. 1 Converts 0.44 cm³ to 4.4 × 10^-7 m³.
  2. 2 Uses ρ = m/V with consistent SI units.
  3. 3 Rearranges correctly for mass.
  4. 4 Obtains 0.00946 kg (9.46 × 10^-3 kg), subject to official error-carried-forward guidance.

Full-mark answer

0.44 cm3=0.44×10−6 m3=4.4×10−7 m30.44\text{ cm}^3=0.44\times10^{-6}\text{ m}^3=4.4\times10^{-7}\text{ m}^3. Since ρ=m/V\rho=m/V, m=ρV=21 500×4.4×10−7=9.46×10−3 kgm=\rho V=21\,500\times4.4\times10^{-7}=9.46\times10^{-3}\text{ kg}.

Why this answer loses marks

I multiplied the density by the volume in cubic centimetres.

The density and volume units must be consistent before using mass = density × volume.

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