Density

The density of a material is described as its mass per unit volume. The mass is usually measure in kilograms (kg) and volume in cubic metres (m³), so density is measured in kg per m³. To illustrate this, think about the materials, lead and balsa wood. If the pieces were identical in weight (see mass and weight), their volumes would be very different since the density of the lead, at 11,340 kg per m³, would be much greater than that of the balsa wood at 198 kg per m³. The density of a particular material relative to the density of water, fresh or salty, affects its ability to float. If the overall density is less dense than water, the object will float (see Floating and Sinking). Thus, balsa wood floats and lead sinks.