How is specific gravity defined?

Specific gravity is defined as the relative weight of a specific volume of liquid compared to an equal volume of distilled water. This definition highlights the relationship between the weight of a liquid and the weight of an equivalent volume of water, which is a standard reference point.

The concept of specific gravity does not depend on the amount of liquid, allowing for easy comparison across different substances. By using distilled water as a baseline, specific gravity provides a dimensionless number that indicates whether a substance is denser or lighter than water, since water has a specific gravity of 1.

This measurement is critical in many fields including aviation and other engineering disciplines, where understanding the behavior of liquids under various conditions is fundamental. It helps in making assessments related to fuel, liquids in the aircraft, and their effect on overall aircraft performance.