Summary
- Density is the ratio of mass to volume.
- Density is a measure of a material's or object's compactness.
- As a scalar quantity it has no direction.
- Density is a way to describe mass in a continuous system
- Units
- The SI unit of density is the kilogram per cubic meter [kg/m3].
- The Gaussian unit of density is the gram per cubic centimeter which is equivalent to a gram per milliliter [1 g/cm3 = 1 g/ml].
- One thousand kilograms per cubic meter equals one gram per cubic centimeter [1,000 kg/m3 = 1 g/cm3].
- Specific gravity is the ratio of the density of a substance to the density of a standard substance.
- The standard substance is usually water for solids and liquids and air for gases.
- The density of liquid water under typical conditions on Earth is approximately 1,000 kg/m3.
- The density of air at room temperature near the surface of the Earth is approximately 1.2 kg/m3.
- Specific gravity is a unitless quantity.