Density is a measure used by physics and chemistry to determine the amount of mass contained in a given volume. Science establishes two types of densities. The actual density or measuring the mass per unit volume, and is generally understood by density. It is calculated with the following formula: density = mass / volume.
Furthermore, there is also the relative density or specific gravity that compares the density of a substance with water. It is defined as the unit weight of the material divided by the unit weight of distilled water at 4 ° C. It is calculated with the following formula: Density = density of substance / density of water. When calculating a density, it is assumed that the density at actual or relative density is used only when specifically requested.
The formula of the density, mass / volume, can be applied to any substance, however this must be homogeneous. Well in Heterogeneous Substances density will be different in different parts. In the present case this problem is what to do is take the density of the various parties and the figures obtained from the average draw.
The density of a substance can be varied by changing the pressure or temperature. In the event that the pressure increases, the density of the material also makes, on the contrary, if the temperature increases, the low density. However for both variations, pressure and temperature, there are exceptions, for example, solids and liquids the effect of temperature and pressure is not significant, unlike the gases is greatly affected.
There is a tool called a densimeter or hydrometer to determine the specific gravity of the liquid. It consists of a cylinder and a bulb (heavy to float) glass which contains therein a scale of grams per cubic centimeter. Pour the liquid into the part of the tall jar until the lower hydrometer float freely, and the scale can see what density of the substance in question. There are several specific types of hydrometers different liquids: breathalyser (alcohol), lactometer (milk), saccharometer (molasses), salímetro (sales), among others.
As the density measures are varied. The system used by the International is kilogram per meter. You can also use gram per cubic centimeter, gram per gallon, gram per cubic foot or pounds per cubic foot.