O-Level Physics Density Practical: Solids, Liquids and Measurements

Density is mass divided by volume. The mass reading is often straightforward; choosing a valid volume measurement takes more thought. A cuboid, an irregular sinking solid and a liquid need different methods.

These are supervised reference methods using supplied specimens and liquids. The trainer checks material suitability and the balance's load range. Follow the lab safety briefing principles and keep liquids away from electrical equipment.

Choose the method that fits the sample

The 2026 O-Level Physics syllabus, 6091, includes density measurements in its practical scope on pages 31-32. The methods below illustrate that family; they do not prescribe the specimen in an examination. The Institute of Physics density collection provides related teaching investigations.

For a regular solid, calculate volume from measured dimensions. For an irregular solid, water displacement is appropriate here only when the approved specimen sinks, remains fully submerged and is insoluble and nonreactive in water. A floating, absorbent or reacting sample needs a different assigned method. For a liquid, obtain its mass by subtracting the empty container's mass from the filled container's mass.

Measure a regular solid