Content
The density is the degree of compaction of the different materials, since this parameter measures the amount of mass that exists per unit volume.
If one package contains Styrofoam pellets, for example, and a second, similarly sized package contains ceramic tiles, it is clear that the second will weigh much more than the first. Density is a characteristic property that allows the different substances to be identified.
For example, him lead has a density of 11.3 g / cm3, the of the milk is 1.03 g / cm3 and that of carbon monoxide, a very toxic gas for humans, is just 0.00125 g / cm3. The solid bodies tend to have higher density than liquids and these in turn have a higher density than gases.
Foam rubber mattresses, which are made with 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 minimum recommended density for making mattresses it is 22 kg / m³, the denser mattresses become heavier but are considered better to avoid problems of low back pain and spinal deformation; they are also more durable.
The porous and less dense materials they are usually useful as temperature and sound insulators. These materials typically float on water, like cork or plastic.
The figurative sense of "dense"
By extension of this concept of physical density is that something is said to be dense, figuratively, when takes a lot of attention or concentration to be understood, either because of how difficult or troublesome it is.
For example, a topic is classified as “dense” when it is conflictive; a book or movie can be called "dense" or "dense" in this sense as well. Even a college subject that requires a lot of study or effort of abstraction or memorization can be classified by students as "heavy."
Population density
On the other hand, population density is a demographic concept that accounts for the number of individuals per unit ofsurface, whether these are humans or animals or plants.
Examples of density
Examples of different densities of chemical elements or complex materials, and population density of cities:
- Naphtha density: 0.70 g / cm3
- Density of ice (at 0 ° C): 0.92 g / cm3
- Mercury density: 13.6 g / cm3
- Density of a standard foam rubber mattress: 28 kg / m3
- Population density of Mexico City (year 2010): 5862 inhabitants / km²
- Paraná pine wood density (dry): 500 kg / m3
- Black locust wood density (dry): 800 kg / m3
- Density of helium (gas with which flying balloons are inflated): 0.000178 g / cm3
- Uranium density: 18.7 g / cm3
- Density of regenerating lenga trees in the Andean-Patagonian forest: 20,000 to 40,000 specimens / ha.
