Density · Year 10
Density tells you how much mass is packed into each unit of volume. It explains why some things float and others sink, and it lets scientists identify materials and check whether a gold crown is really pure gold.
Key facts
- Density ρ = mass ÷ volume (g/cm³ or kg/m³). Rearranged: m = ρV and V = m ÷ ρ.
- Water: 1.0 g/cm³ = 1,000 kg/m³. To convert g/cm³ to kg/m³ multiply by 1,000.
- Regular shapes: find the volume by measuring (cuboid: length × width × height).
- Irregular shapes: find the volume by displacement (measuring cylinder or overflow can).
- Objects less dense than a liquid float in it; denser ones sink.
- Mixtures: density = total mass ÷ total volume (not the average of the densities).