Specific gravity

Definition

Specific gravity is the ratio of the density of a substance to the density of a reference substance, typically water for liquids and solids. It is a dimensionless quantity.

5 Must Know Facts For Your Next Test

1. Specific gravity is dimensionless because it is a ratio.
2. The specific gravity of water at 4°C (39°F) is exactly 1.
3. If an object's specific gravity is less than 1, it will float in water; if greater than 1, it will sink.
4. Specific gravity can be used to identify substances and assess their purity.
5. It plays a critical role in Archimedes' Principle when calculating buoyant forces.

Review Questions

• What does it mean if an object has a specific gravity less than one?
• How does specific gravity relate to Archimedes’ Principle?
• Why is specific gravity considered a dimensionless quantity?

Related terms

Density:

Mass per unit volume of a substance, typically measured in kilograms per cubic meter (kg/m^3).

Buoyant Force:

The upward force exerted by a fluid on an immersed object, equal to the weight of fluid displaced by the object.

Archimedes’ Principle: \text{A principle stating that any object submerged in a fluid experiences a buoyant force equal to the weight of the fluid displaced by the object.}