Question

what is relative density?

Answer 1

the ratio of the density of a substance to the density of a standard, usually water for a liquid or solid, and air for a gas.

Answer 2

The ratio of the density of a substance to the density of water is known as relative density.

The density of water is 1000kg/m^3.

By checking the relative density, one can tell whether the object will sink or float.

Hope it helps :)