1. What is Relative Density (Specific Gravity)?

Definition: Relative density (RD), or specific gravity, is the ratio of the density of a substance to the density of a reference material (typically water).

Purpose: It provides a dimensionless quantity that describes how dense a material is compared to water, which is useful in various scientific and engineering applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( RD \) — Relative density (unitless)
• \( \rho \) — Density of the material (kg/m³)
• \( \rho_{water} \) — Density of water (typically 1000 kg/m³)

Explanation: The material's density is divided by water's density to get a ratio that indicates how much denser (RD > 1) or less dense (RD < 1) the material is compared to water.

3. Importance of Relative Density

Details: Relative density is crucial in fluid mechanics, material science, and geology. It helps determine buoyancy, purity of substances, and identification of minerals.

4. Using the Calculator

Tips: Enter the material density in kg/m³ and water density (default 1000 kg/m³). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is water used as the reference?
A: Water is used because it's abundant, well-studied, and has a density of exactly 1000 kg/m³ at 4°C (standard reference condition).

Q2: What does a relative density of 2.5 mean?
A: It means the material is 2.5 times denser than water. If placed in water, it would sink as it's denser than water.

Q3: Can I use different reference substances?
A: Yes, though water is standard. For gases, air is often used as the reference (density ~1.225 kg/m³ at sea level).

Q4: How does temperature affect the calculation?
A: Both material and water densities change with temperature. For precise work, use densities measured at the same temperature.

Q5: What are typical relative density values?
A: Most rocks: 2-3; Metals: 2-11 (gold ~19); Wood: 0.3-0.9; Ice: 0.92 (floats on water).