Its word comes from the Latin ( densĭtas, -ātis ). Density is the quality of the dense, or the accumulation of a large number of elements or individuals in a given space.
In the field of demography, we speak of population density, which is the number of inhabitants times the number of square kilometers that a territory or surface has. This density is used to know the degree of concentration of the population.
In science settings, density is a characteristic physical property of any matter. It is the magnitude that expresses the relationship between the mass and the volume of a body (m / v); that is, it is the amount of matter (mass) that a body has in one unit of volume. Its unit in the International System is the kilogram per cubic meter, but for practical reasons the gram per cubic centimeter is normally used.
Each substance, in its natural state, has a characteristic density. For example, 1 liter of water in a liquid state has a mass of 1 kilogram: we say that the density of water is 1 kg / l.
Sometimes we notice that some bodies float in water and others sink, this is due to the difference in density between them. Bodies less dense than water, such as a piece of wood or oil, float on top of it, while those denser, such as an egg or a stone, tend to sink to the bottom of the water.
The comparison of the density of a body with the density of another that is taken as a unit or reference is known as relative density. This density is dimensionless (without units), since it is defined as the quotient or ratio of two densities.
The density can be obtained in several ways. For a solid body, we can weigh it on a scale to find out its mass, and immerse it in a glass of water to calculate its volume by difference between the levels of the liquid. Obtaining the mass and volume of the body, its density can be calculated.
To measure the density of a liquid, an instrument called a density meter is used, which provides a direct reading of the density, a graduated glass can also be used, where we first have to weigh the empty glass and then filled with the liquid, and subtracting we obtain its mass. We see the volume it occupies on the graduated scale.
