What does specific gravity measure?

• A. The viscosity of a substance
• B. The density of a substance in relation to water
• C. The weight of a substance
• D. The moisture content of a substance

Answer: (B)

Specific gravity is a dimensionless quantity that measures the density of a substance in relation to the density of water. It is calculated by taking the density of the substance and dividing it by the density of water at a specific temperature, typically 4 degrees Celsius where water reaches its maximum density.

This measurement is critical in fields such as materials science, engineering, and construction, as it provides insight into the behavior of materials, such as how they will perform when compacted or mixed into other materials. For instance, knowing the specific gravity of aggregates used in paving can help ensure the right balance for optimal performance and durability of paved surfaces.

The concept of specific gravity allows for the comparison of material densities without the unit dependence, making it a more universally applicable measurement in scientific assessments.