Question

Explain the statement “relative density of brass is 8.4”.

Answer 1

Hint: Density is a property of material which varies from one material to another. It may be defined as how closer the molecules inside a body are bound. Mathematically it is defined as the mass present in unit volume. Hence, density is the ratio of mass and volume of the given sample.

Complete answer:
When we say relative word, it means we are comparing a quantity with another quantity in reference. For example “relative velocity of car A with respect to car B is 50 m/s”. By this statement we mean that the velocity of car A is 50 m/s more than that of car B, actual velocity of A may be 100 m/s. Hence we can compare any two quantities.
Similar case is with relative density. It may be defined as the ratio of density of substance to that of density of water. It is very important to note that in relative density, generally we take water as a reference point but we can take other fluids also. Relative density gives the measure of how dense a fluid/material is more than water.
Hence, by the statement “relative density of brass is 8.4”, we mean that brass is 8.4 times more dense than water.

Note:
Relative density can be less than, equal to or more than unity. For it to be less than 1, it means that the material is even lighter than water. The main use of this term is that we can directly say that one body will float on water or not. For instance, as brass is denser than water means that it will sink if placed on the surface of water.