Question

What does specific gravity meansand how does specific gravity related to solid materials?

Answer 1

Specific gravity is the ratio of the density of a substance with the density of a reference system.

Explanation:

The reference substance is usually taken to be water.
So the specific gravity of a solid would mean how many times denser it is than water.
In case of solids specific gravity is usually calculated as the ratio of it's weight in air to the difference between it's weight in air and it's weight when completely immersed in water.
`S.G= W_(air)/(W_(air)-W_(immersed))`
Since density of a substance depends on temperature and pressure, specific gravity also varies with those.