Describe an experiment, using AA body weighs W1 gf in air and when immersed in a liquid, it weighs W2 gf, while it weighs W3 gf on immersing it in water. Find: (i) volume of the body (ii) upthrust due to liquid (iii) relative density of the solid and (iv) relative density of the liquid.rchimedes’ principle, to find the relative density of a liquid.

Weight of the body in air = W₁ gf

Weight of the body in liquid = W₂ gf

Weight of the body in water = W₃ gf

(i) Let V be the volume of the body.

Upthrust due to water = loss in weight when immersed in water = (W₁ – W₃) gf    …[Eq 1]

Weight of water displaced = Volume of water displaced × density of water × g

The volume of water displaced = Volume of the body = V

Density of water = 1 g cm^-3

∴ Weight of water displaced = V × 1 × g = V gf     …[Eq 2]

But the weight of water displaced is equal to the upthrust due to water

∴ From eqns 1 & 2,

V = (W₁ – W₃) cm³

∴ Volume of the body = V = (W₁ – W₃) cm³

(ii) Upthrust due to liquid = loss in weight when immersed in liquid = (W₁ – W₂) gf

(iii) Relative density of the solid

RD of solid = W_1\over W_1 - W_3

(iv) Relative density of the liquid

RD of liquid = W_1 - W_2\over W_1 - W_3