What is the Difference Between Specific Gravity and Specific Weight?
🆚 Go to Comparative Table 🆚The main difference between specific gravity and specific weight lies in their definitions and the fact that one is a relative quantity while the other is an absolute quantity.
Specific Gravity is a dimensionless quantity that provides a measure of how much denser or lighter a substance is compared to a reference substance. It is defined as the ratio of the density of the given material to the density of the reference material. For liquids and solids, the reference substance is water at 4°C, where the density of water is 1000 kg/m³. For gases, the reference substance is air at a specified temperature and pressure, such as 25°C and 1 atm.
Specific Weight is defined as weight per unit volume. It is a force and has dimensions of mass × length⁻² × time⁻². The SI unit for specific weight is N/m³, while the imperial unit is lb/ft³. Specific weight is dependent on the gravitational field, unlike specific gravity.
In summary:
- Specific Gravity is a dimensionless quantity that compares the density of a substance to a reference substance.
- Specific Weight is a measure of weight per unit volume and depends on the gravitational field.
Comparative Table: Specific Gravity vs Specific Weight
The main difference between specific gravity and specific weight lies in their definitions and units. Here is a table summarizing the differences:
| Property | Definition | Units |
|---|---|---|
| Specific Gravity (SG) | The ratio of the density of a substance to the density of a reference substance (usually water). It is a dimensionless property. | - |
| Specific Weight (γ) | The weight per unit volume of a substance, defined as the product of its density and the acceleration of gravity. | N/m³ or lbf/ft³ |
Specific gravity is a ratio that compares the density of a substance to the density of a reference substance, typically water for liquids and solids, and air for gases. It is a dimensionless property, meaning it has no unit of measurement. On the other hand, specific weight is a force per unit volume, and it is calculated using the following formula:
$$\gamma = \rho g$$
where:
- $$\gamma$$ is the specific weight (N/m³ or lbf/ft³)
- $$\rho$$ is the density of the substance (kg/m³ or slugs/ft³)
- $$g$$ is the acceleration of gravity (9.807 m/s² or 32.174 ft/s²)
In summary, specific gravity is a ratio that compares the density of a substance to the density of a reference substance, while specific weight is a force per unit volume that depends on the density and acceleration of gravity.
- Density vs Specific Gravity
- Relative Density vs Specific Gravity
- Bulk Density vs Specific Gravity
- Gravity vs Weight
- Density vs Weight
- Mass vs Weight
- Mass vs Weight
- Volume vs Specific Volume
- Gram Equivalent vs Equivalent Weight
- Gram Molecular Weight vs Gram Equivalent Weight
- Mass vs Density
- Gross Weight vs Net Weight
- Density vs Bulk Density
- Relative Density vs Density
- Body Mass vs Body Weight
- Exact Mass vs Molecular Weight
- Formula Weight vs Molecular Weight
- Gravity vs Gravitation
- Volume vs Density