Arithmetic density refers to the total number of people per unit area of land, calculated by dividing the population by the total land area. In contrast, physiological density measures the number of people per unit area of arable land, focusing on the population supported by land suitable for agriculture. This distinction highlights how arithmetic density can be misleading in assessing population pressure on resources, while physiological density provides insight into the sustainability of agricultural practices in relation to population.
density = mass/volume
The shape of an object is not enough to calculate its density. You also need its mass and then Density = Mass/Volume.
Bulk density = dry weight / volume, then by knowing the dry weight and bulk density we can calculate the volume.
Density is found when you divide the mass and the volume.