Question

A solid weighs 30gf in air and 25gf when completely immersed in water. Its density is

Answer 1

Given, weight of solid in air = 30 gf and weight of solid in liquid = 26 gfRD of liquid = 0.8

Therefore, Density of liquid = 0.8 g cm‐³

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

Weight of liquid displaced Volume of liquid

displaced xdensity of liquid x g

= V x0.8xg dyne

= V x0.8 gf

Loss in the weight of the solid when immersed in the

liquid = 30 - 26 = 4gf

But the weight of liquid displaced is equal to the loss in weight of the solid when immersed in liquid.

Therefore, Vx0.8 = 4 or V =

$\frac{4}{0.5} = {5cm}^{3}$

(ii) Given, weight of solid = 30gf Therefore, Mass of solid = 30 g

Density of solid=

$\frac{mass}{volume} = \frac{30}{5} = 6g {cm}^{ - 3}$

Hence relative density of solid = 6