Density

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

  ρ =	m
  	V

• 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.