The density of matter and life applications of density
Each substance has its own density , The density is a physical property of the matter as each element and compound has its own density , and it varies with the temperature and the pressure .
The mass is the amount of the matter that the body contains , and its measuring unit is ( kg ) or ( gm ) , The volume is the space that a substance occupies , and the density is the mass of unit volume of the matter or it is the mass of one cubic centimetre of the matter .
Equal masses of different substances have different volumes , and equal volumes of different substances have different masses as they have different densities , Some substances float on the water surface and others sink in the water due to the difference in their densities .
The materials which have higher density than the water sink in it such as iron nails and metallic coins , while the materials which have lower density than the water float on its surface such as the wood , the cork , the ice and the drops of oil .
Life applications on the density
The water is not used to put out the petrol fires as the density of petrol is less than of the water so , the petrol floats on the water surface and the water does not put out the fire .
The balloons filled with hydrogen or helium rise up in the air carrying flags during the festivals as the densities of hydrogen and helium are less than the density of the air .
The determination of the change in the density of the matter is taken as an evidence of the purity of the matter as the determination of the quality of the milk .