Question

The weight of a body in water is one third of its weight in air.Water is the density of the material of the body?

Answer 1

Given,

Weight of body in water is $\frac{1}{3}$ of total weight in air,

Mean, buoyancy force in water is $\frac{2}{3}$of total weight in air

Volume of body, $V$

Density of water & body, ${\rho }_w\&{\rho }_b$

Apply Archimedes principle

Buoyancy force = weight of water displaces = $\frac{2}{3}$ weight of body in air

${\rho }_{w}Vg=\frac{2}{3}{\rho }_{b}Vg$

${\rho }_b=1.5{\rho }_w$

Density of body is $1.5$ time the density of water.