GCSE Physics · Edexcel 1PH0 · Topic 14A
Density
Key points
- Density is mass per unit volume: , in kg/m³ or g/cm³ (1 g/cm³ = 1000 kg/m³).
- Solids are usually densest, as particles are closely packed; gases are least dense, as particles are widely spaced.
- Measure density of a regular object: find mass on a balance and calculate volume from measurements.
- For an irregular object, find volume by displacement using a eureka can or measuring cylinder (core practical).
- For a liquid, measure the mass of a known volume in a measuring cylinder (subtract the empty mass).
- An object floats in water if its density is less than about 1 g/cm³ (1000 kg/m³).
Topic notesPremium
Density tells you how much mass is packed into each unit of volume. It explains why some objects float and others sink, and it is one of the easiest quantities to measure in the laboratory.
Unlock the full notes with Premium
Premium includes full topic notes, the paper generator, self-quizzes and progress tracking.
Practise this topicPremium
Premium members can generate an exam-style paper with a mark scheme, or take a quick quiz, on Density.