## AQA GCSE Density

**Density**

Density is the amount of mass per unit volume.

Gases tend to have low density, whilst solids and liquids have higher density.

**Calculation example**

1.A solid metal bar has a mass of 400g and a volume of 0.5m^{3}. Calculate the density of the metal bar.

Convert 400g to kg, so this is 0.4kg

Density = mass/volume

Density = 0.4/0.5 = 0.8 kg/m^{3}

2.Calculate the volume of a gold bar which has a mass of 2000kg and a density of 19300 kg/m^{3}.

Volume = mass/density

Volume = 2000/19300 = 0.104m^{3}

3. Concrete has a density of 2200kg/m^{3}. Use the diagram below to answer the following question.

The concrete slab above has a mass of 4.6kg and is a cuboid shape with a length of 0.4m and width of 0.4m. Calculate the thickness of the concrete slab.

Density = mass/volume

Volume = mass/density

Volume = 4.6/2300 = 2 x 10^{-3} m^{3}

Volume = length x width x thickness

2 x 10^{-3} = 0.4 x 0.4 x thickness

Thickness = 2 x 10^{-3}/(0.4 x 0.4) = 0.0125m

Thickness = 0.0125m, or 1.25cm

**Practice Questio****ns**

1.A small gemstone has a mass of 60g and a volume of 1.5 x 10^{-2} m^{3}. Calculate the density in kg/m^{3}

2.Calculate the mass of a sphere which has a volume of 9 x 10^{-2 }m^{3} and density of 3.2 x 10^{-3 }kg/m^{3}.

3. Use the image below of a roll of plastic film to help you to answer the following question.

The film has a density of 3000 kg/m^{3} and mass of 20kg. If the film is uncoiled and laid flat it has a length of 3m x 1m. Calculate the thickness of the film.

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