Question

A body weighs 450 gf in air and 310 gf when completely immersed in water. Find :
(i) the volume of the body,
(ii) the loss in weight of the body, and
(iii) the upthrust on the body. State the assumption made in part (i).

Answer 1

(i) Loss in weight of the body = 450 gf - 310 gf = 140 gf
This means mass of water displaced = 140 g
So, volume of the body = Volume of water displaced = $\frac{m}{d}=\frac{140g}{1g/c{m}^3}=140g$

(ii) Loss in weight of the body = 450 gf - 310 gf = 140 gf

(iii) Upthrust = Loss in weight = 140 gf

The assumption made is that the volume of the body is equal to the volume of water displaced.