Definition of Specific Gravity – What is, Meaning and Concept

The weight is the force exerted by the planet to attract bodies. The magnitude of the force in question is also known as the weight. Weight, on the other hand, is often used as a synonym for mass, although this concept specifically names the body’s level of matter (beyond the gravitational force).

With this in mind, we can define the notion of specific weight, which is the link between the weight of a certain substance and the volume correspondent. It can be expressed in newtons over cubic meter (at International system) or in kiloponds over cubic meter (at Technical system).

Specific weight and density

It is important to note that the kilopond (also know as kilogram-force) is the force that exerts the planet’s gravity Earth over a mass of one kilogram. This means that the value of the specific weight expressed in kiloponds over cubic meter is equivalent to the value of the density (which is expressed in kilograms over cubic meter).

Specific gravity, therefore, is the weight of a substance per unit volume. The density, on the other hand, refers to the mass of a substance per unit volume and is obtained through the division of a known mass of the material in question by its volume.

Although density and specific gravity are different concepts, they are closely related to each other. For example, if we take the formula of the weight of a bodyP = m. g, mass times acceleration due to gravity) and we use it to substitute the variable p in the formula for specific gravity (Pe = p / V, weight over volume), we obtain the following: Pe = mg / V. This can also be expressed as Pe = m / V. g And, since the density is the mass over the volume, it can be concluded that the specific weight is equal to the density multiplied by the acceleration of gravity: Pe = d. g.

If we take the case of frozen water, for example, we will note that its specific gravity is 9170 newtons over cubic meter, while its density is 0.917 kilograms per cubic meter.

Usefulness of the concept

Know the specific gravity of a Body it can be very important at an industrial level to determine what are the best conditions for its processing, to mention one possibility. Everything will depend on the characteristics of the product that is planned to obtain.

Thanks to the determination of the specific weight, and also in some cases of the density, it is possible to obtain the best physical and physiological quality of certain products, such as rice, wine (through the analysis of the must, since the higher the weight specific, higher sugar content), gems and cement.

What is relative specific gravity

The relative specific gravity of a given substance is called its unit weight divided by the unit weight of the substance. Water when distilled at a temperature of 4 ° C. This value is used to predict the unit weight of a soil, to perform hydrometer analysis, and to calculate the void ratio of a soil. For grains, it is the value considered average and is generally used to classify their minerals. It is worth mentioning that this concept is also called specific gravity.

When you want to determine the relative specific gravity of a I usually Two procedures are established: one for those consisting of particles smaller than 5 millimeters; another for the rest. By means of a sieve number 4 it is possible to carry out said classification, to apply the method that corresponds to each sample, after which the weighted average of both must be obtained.