How is specific gravity defined in relation to density?

• A. Density of solid / density of water
• B. Density of water / density of solid
• C. Mass of solid / volume of solid
• D. Volume of water / volume of solid

Answer: (A)

Specific gravity is defined as the ratio of the density of a solid to the density of water. This concept is crucial in various applications, especially in fields like engineering and materials science, where understanding the properties of materials is essential.

The correct answer indicates that to determine the specific gravity of a material, you take the density of the solid (mass per unit volume) and divide it by the density of water. Since the density of water at standard temperature and pressure (approximately 4°C) is taken as a reference point (usually 1 g/cm³ or 1000 kg/m³), this ratio allows for a dimensionless number that describes how dense the material is relative to water.

Understanding specific gravity is beneficial because it helps in characterizing materials, assessing buoyancy, and understanding how different materials might behave in various environments (e.g., submerged in water). It also provides practical insights for grading and separating materials based on density.

The other options do not accurately define specific gravity, as they either invert the relationship or focus on either mass or volume without providing a ratio to the density of water, which is fundamental in calculating specific gravity.