Question

3. A solid weighs 30 gf in air and 26 gf when completely immersed in a liquid of relative density 0·8. Find : (i) the volume of solid, and (ii) the relative density of solid. in mir W 30 of and weight of​

Answer 1

Answer:

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}

0.5

4

=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}

volume

mass

=

5

30

=6gcm

−3

Hence relative density of solid = 6