Page 22 - Pressure 10 class

Density; Mass per unit volume of a substance is called density.

3
SI Unit : Kg/ m ( Kilogram per cubic meter)
3
CGS Unit : g/ cm ( Centimeter per cubic meter)
Formula ; Density (d) = Mass of a substance (m)/ Volume of s substance(v)

i.e d = m/v
0
Relative Density; The ratio of density of a substance to the density of water at 4 C is called
relative density or specific gravity. It has no unit. (Since it is the ratio of two densities.)

Formula;

Relative Density(R.D) = Density of a substance
0
Density of water at 4 C
➢ The relative density of aluminum is 2.7, it means the ratio of density of aluminum to
0
the density of pure water at 4 C is 2.7.

Difference between Density and Relative Density.

Density Relative Density

1. Mass per unit volume of a substance 1. The ratio of density of a substance to the density
0
is called density. of water at 4 C is called relative density

2. The SI unit of density is Kg/ m 3. 2. Relative density has no unit.

July 30, 2020 Taranath Baral/GC Shiba/Suraj Thapaliya 22