Relative density is a measure of how dense a substance is compared to water. It is expressed as a ratio of the density of the substance to the density of water. Water has a density of 1 kg/m³, so the relative density of a substance is equal to its density in kg/m³ divided by 1.
For example, the density of gold is 19.3 kg/m³. The relative density of gold is therefore 19.3 kg/m³ / 1 kg/m³ = 19.3. This means that gold is 19.3 times denser than water.
Relative density is a useful concept because it allows us to compare the densities of different substances without having to know their actual densities. For example, we can say that gold is denser than aluminum without having to know the exact densities of gold and aluminum.
Here is a table showing the relative densities of some common substances:
| Substance | Relative Density |
|---|---|
| Water | 1 |
| Aluminum | 2.7 |
| Iron | 7.8 |
| Copper | 8.9 |
| Gold | 19.3 |
| Lead | 11.3 |
As you can see, the relative densities of these substances range from 1 to 19.3. This means that some substances are much denser than others. For example, gold is almost 20 times denser than water.
