Density is a measure of the quantity of mass in a unit volume of material. Unit weight is a measure of the weight of a unit volume of material. Both can be used interchangeably. The units of density are ton/m³, kg/m³ or g/cm³. The following are the basic weight relations:
The ratio of the mass of water present to the mass of solid particles is called the water content (w), or sometimes the moisture content.
The ratio of the mass of the solid particle to the mass of the volume particles.
The ratio of the mass of the solid particle to the mass of the total volume.
The ratio of the total weight of the soile to the total volume.
Submerged unit weight or Buoyant unit weight is the effective mass per unit volume when the soil is submerged below standing water or below the ground water table.
Specific gravity is the ratio of the unit weight of the soil to the unit weight of water. For most inorganic soil, the specif gravity lies between 2.6 to 2.8