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Grades 9 and 10 Intermediate About 20 min Version 1 Awaiting review Premium

Finding the density of solids

Density tells you how much mass is packed into each unit of volume: density = mass ÷ volume, measured in g/cm³ or kg/m³ (1 g/cm³ = 1000 kg/m³). Measure mass with a balance. For a regular solid such as a block, volume = length × width × height. For an irregular solid such as a stone, find the volume by displacement. Every pure material has its own density, so density helps identify what something is made of. Objects less dense than water (1 g/cm³) float in it.

What you will learn

  • Measure mass with a balance and calculate the volume of a regular solid.
  • Find the volume of an irregular solid by displacement.
  • Calculate density and use it to compare materials and predict floating.

Before you start

  • Measure length with a ruler and read a measuring cylinder.

Materials

  • Aluminium cube, iron block, wooden block, rubber eraser and a stone

Equipment

  • Electronic balance
  • Ruler
  • 100 mL measuring cylinder with 50 mL of water

Procedure

  1. Put the aluminium cube on the balance, measure its sides and record its density.
  2. Find the stone's volume by displacement and record its density.
  3. Measure the aluminium cube by displacement too and check you get the same density.
  4. Find the density of the wooden block and see what happens when you try displacement.

How this simulation is simplified

  • The cylinder starts with 50 mL of water.
  • A floating object is not pushed under, so it displaces only its own mass of water.