The method and the results are on the density lab. Do the analysis yourself first, then check the answers below.
Quick answer: Density is the mass of a material per unit of volume, found with the formula density = mass ÷ volume. These answers go with the grade 6 science lab on density: the graph, the calculations, the uncertainties and the conclusion explained, for all 7 analysis questions.
These model answers use the sample readings in the table. Your own measurements will vary a little, but the densities should stay close to 1.00 g/cm³ for water and 0.92 g/cm³ for sunflower oil.
The points lie close to a straight line through the origin, so mass is proportional to volume. Gradient = (73.5 − 18.4) ÷ (80 − 20) = 55.1 ÷ 60 = 0.918 g/cm³, which is the density.
Question 5 Prediction for oil
The oil’s density (0.92) is less than that of water (1.00), so it floats on top of the water.
Question 6 Wooden block
V = 8.0 × 4.0 × 2.0 = 64 cm³. ρ = 38.4 ÷ 64 = 0.60 g/cm³. This is less than 1.00 so the block floats, with about 60 % of its volume under water.
Question 7 Sources of error
Oil clinging to the cylinder walls means that less oil is weighed than was measured; leave it to drain, and use the same cylinder throughout. Misreading the meniscus gives a wrong volume; read at eye level. Any two valid errors are accepted.
