Calculation Of Specific Gravity:-
The Specific Gravity (it is also written as sp.gr.) of a substance is the ratio of the weight of a given volume of the substance to the weight of an equal volume of some standard substance (which is taken as water at 4degreeC)
Obviously it is a pure number and processes no dimensions.
Hence the Specific gravity of a substance
=(the weight of volume v of the substance)/(the weight of volume v of the standard substance)
=(the weight of a unit volume of the substance)/(the weight of a unit volume of the standard substance)
=(the mass of a unit volume of the substance)/(the mass of a unit volume of the standard substance) (as weight=mass*g)
=(the density of the substance)/(the density of standard substance)
This is the final step for Specific Gravity.
True specific gravity can be expressed mathematically as:
The apparent specific gravity is simply the ratio of the weights of equal volumes of sample and water in air:
It can be shown that true specific gravity can be computed from different properties:
where is the local acceleration due to gravity, is the volume of the sample and of water (the same for both), is the density of the sample, is the density of water and represents a weight obtained in vacuum.