# Density Back to Encyclopedia

Density is quite simply defined as the mass per unit volume of a material. Density can be defined as a measure of the relative heaviness of any object with a constant volume. Density is such an important quantity in fluid mechanism because it defines and determines the inter-relation of objects or fluids or gases to one another. All matter has a density with some measured in relation to others.

Density was first postulated and documented by the scientist and mathematician Archimides. Archimides simply discovered that if a denser object is immersed in a less dense liquid, some of the liquid is displaced and after calculation found that the volume of liquid displaced is the same in volume as the volume of the object. This has universally been accepted as the standard for measurement of density in every scientific ramification. Density is also often referred to as regard population and how close people are packed together in a certain settlement. It is this aspect of density that is referred to as population density.

Density is a very important quantity in science, mathematically as stated above density is deduced as mass per unit volume or more clearly mass divided by volume. Therefore, if one knows the mass of a substance or a material and knows the volume, one can easily calculate its density. Consequently, the S.I unit for density is kg/m3. Though its unit can be further expanded or compounded depending on the measuring scale used, the density of a material remains the same so long as the mass and volume does not change.

Density finds its application in wide varieties of science, but notably it helps to differentiate between two different materials which also helps explain how different materials relate with each other. One major phenomenon caused by density is the phenomenon of floatation. Floatation is the process whereby an object or fluid tends to hover or slide on top of another fluid without sinking. This is made clearer with the use of density as thus, an object that is less dense, tends to float on a denser fluid. This floatation helps in the sailing of ships and boats preventing them from sinking deep into the sea. Density also helps in determining the volume of an irregular solid by immersing them in a liquid of known volume and density and measuring the amount of liquid displaced. Due to uniformity, water is widely used as the standard liquid for measuring density. This is achievable through the concept of relative density.

Density can be altered or affected by variable factors. One of the important factors that will affect density is temperature because if an object is heated it tends to expand. This expansion will spark a change in volume of the object, thereby reducing its density. Impurities present in a fluid can alter the density of such fluids by either increasing them or decreasing them. 