Difference Between Density and Specific Gravity

density vs gravity

Density and specific gravity are very commonly used. However, these two terms are often confused.

Specific gravity can be defined as the ratio of a substance’s weight to the weight of the same volume of water at four degrees Celsius. Specific gravity can be calculated by dividing the density of a substance with the density of water. This means that a substance having a specific gravity of 7.0 will be seven times as dense as water.

Density can be defined as the mass of an object per unit volume. In order to calculate density, the weight and volume of the substance should be known. It can be calculated by dividing the weight by the volume.

Density has the symbol ‘P’ and its unit is kilogram per cubic meter. It should also be noted that pressure and temperature could affect the density of substances. If the pressure is increased, the volume of the substance increases, which would increase the density. If the temperature increases, the volume increases, which would lead to a decrease in the density.

When compared to density, specific gravity does not have an SI unit. While density is expressed as an absolute term, specific gravity is considered a relative term. And this is why specific gravity does not have a standard unit. Just like density, temperature and pressure have an influence on specific gravity. In the industries, specific gravity is used to measure concentrations of solutions.

Summary
1. Specific gravity can be defined as ratio of a substance’s weight to the weight of the same volume of water at four    degrees Celsius.
2. Density can be defined as the mass of an object per unit volume.
3. Specific gravity can be calculated by dividing the density of a substance with the density of water. This means that a substance having specific gravity of 7.0 will be seven times as dense as water.
4. In order to calculate density, the weight and volume of the substance should be known. It can be calculated by dividing the weight by the volume.
5. Density is expressed as an absolute term, specific gravity is considered a relative term.
6. Density has the symbol ‘P’ and its unit is kilogram per cubic meter. When compared to density, specific gravity does not have a SI unit.
7. In the industries, specific gravity is used to measure concentrations of solutions.

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