Finding the density of solids
Weigh blocks and a stone on a balance, find their volume by measuring their sides or by displacement, and calculate their density.
Core concept
Density = mass ÷ volume, a property that helps identify a material
Topic: Measurement
density: How much mass is packed into a space. Things less dense than water float. All key words tells you how much mass: How much matter something has, measured in grams or kilograms. It is the same everywhere. All key words is packed into each unit of volume: How much space something takes up, measured in millilitres or cubic centimetres. All key words: 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
- Put the aluminium cube on the balance, measure its sides and record its density.
- Find the stone's volume by displacement and record its density.
- Measure the aluminium cube by displacement too and check you get the same density.
- 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.