# 10 Examples of Density

The density It is a quantity that measures the amount of mass that a material has per unit volume.

The density of a substance depends on the temperature and the Pressure. Generally, as temperature increases, the density of a material decreases. For example, lead has a density of 11.3 g/cm3 at 20 ºC, that of milk is 1.03 g/cm3 at 15 ºC and that of carbon monoxide, a highly toxic gas for humans, is barely 0.00125 g/cm3 at 0ºC. Solid bodies tend to have higher density than liquids and these in turn have higher density than gases.

Density can be classified into:

• Density or absolute density. It is the ratio of the mass to the volume of a material.

Where (X), m(X) Y V(X) are the density, mass and volume of the substance X respectively.

• Relative density. It is the ratio of the density of one material to the density of another.

Where relative is the relative density of the substance of the substance X relative to the density of the substance Y, and where (X) Y (Y) are the densities of the substances X and Y respectively.

• Apparent density. It is used to calculate the density of porous materials that may have certain substances incorporated into their pores.

If a package contains Styrofoam balls, for example, and a second pack of similar size contains ceramic tiles, it is clear that the second is going to weigh much more than the first. Density is a characteristic property that allows us to identify different substances.

The foam mattresses, which are made of a material called polyurethane or polyester, can have different densities and this determines, in part, their quality and durability. In this case, the density of the foam is expressed in kilograms per cubic meter (kg/m3).

The recommended minimum density for making mattresses is 22 kg/m³. The denser mattresses become heavier but are considered better to avoid problems of low back pain and spinal deformity; They are also more durable.

The materials porous and less dense They are often useful as temperature and sound insulators. These materials typically float on water, like cork or plastic.

### The figurative meaning of “thick”

By extension of this concept of physical density, it is said, in a figurative sense (that is, not literally) that something is dense when it demands a lot of energy. attention or concentration to be understood, either because of how difficult or how problematic it is.

For example, a subject is qualified as “dense” when it is controversial; a book or a movie can be nicknamed “dense” or “dense” in this sense as well. Even a subject of study that requires a lot of abstraction or memorization effort can be described by students as “dense”.

### population density

On the other hand, population density is a demographic concept which accounts for the number of individuals per surface unit (humans, animals or plants).

### Examples of density

Examples of different densities of chemical elements or of complex materials, and of population density of cities, are given below:

1. Naphtha density: 0.70 g/cm3
2. Ice density (at 0 ºC): 0.92 g/cm3
3. Mercury density (at 20 ºC): 13.6 g/cm3
4. Density of a standard foam rubber mattress: 28 kg/m3
5. Population density of Mexico City (year 2010): 5862 inhabitants/km²
6. Density of Paraná pine wood (dry): 500 kg/m3
7. Black carob wood density (dry) : 800 kg/m3
8. Density of helium (gas with which flying balloons are inflated) (at 20 ºC): 0.000178 g/cm3
9. Uranium density (at 20 °C): 19.1 g/cm3
10. Density of regenerating trees in the Andean-Patagonian forest: 20,000 to 40,000 specimens/ha.