As
you well aware that all materials having individual properties and weights
based on the density. How we can compare the different materials in a same
platform. Since water has a density of 1 gram/cm3, and since all of the units
cancel, specific gravity is the same number as density but without any units
(adimensional).
A 1000kg of pure water
= 1 cubic metre. Pure water was chosen as the 'base line' for specific gravity
and given the value of 1. The specific gravity of all other materials are
compared to water as a fraction heavier or lighter density. For example,
beryllium has a specific gravity (sg) of 1.84 (1840 kg/cu.m)
As specific gravity is just a comparison, it can be applied across any units.
The density of pure water is also 62.4 lbs/cu.ft (pounds per cubic foot) and if
we know that a sample of aluminium has a sg of 2.5 then we can calculate that
its density is 2.5 x 62.4 = 156 lbs/cu.ft.
Note, kg/cu.m divided by 16.02 = lbs/cu.ft
Note, kg/cu.m divided by 16.02 = lbs/cu.ft
One
handy metric link between units to remember is that 1 Litre [1000cc] of pure
water weighs 1 kilogram. Equally, 1 millilitre of pure water has a mass of 1
gram or 1mL = 1g. The upper-case L for litre is preferable as the lower case
can be confused with the figure one, however it is common to see ml for millilitres
on bottles.
