Cambridge Secondary (7-9). Stage 9. Science. Learner's Book - Unit 3: Forces and energy - Question 6

Look at the densities of these materials: pine wood 0.41 g/cm³; polycarbonate 1.2 g/cm³; polythene 0.95 g/cm³; water 1.0 g/cm³. Explain why the material will sink in water.