Define relative density.Give its mathematical form

(i)Define relative density.Give its mathematical form.
(ii)The mass of an iron cube having an edge length 1.5 cm is 50 g. Find its density.
(iii)The volume of a 250 g sealed tin is 400 cubic cm. Find the density of the tin in g ${{cc}^{-1}}$. State, if the object would sink or ‘ float in water.

(i) The relative density of a substance is the ratio of its density to that of water.
Relative velocity of substance = Density of substance / Density of Water
In other words, Relative density of substance = Mass of substance / Volume of the substance x Volume of water / Mass of water
(ii)Given that , mass of the cube = 50 g
Side of the cube = 1.5 cm
Volume of the cube = ${{1.5}^{3}}$ ${{cm}^{3}}$
Density = Mass / Volume = 50/ 3.375 = 14.81 ${{cm}^{-3}}$
(iii) Given that , mass ,m =250g
Volume,V = 400cc
Density = Mass / Volume = 250/400 = 0.625 g ${{cc}^{-1}}$
As we know that, density of water = 1 g ${{cc}^{-1}}$. So, density of tin is less than that of water and hence tin will float.