Question

The volume of $50$g of a substance is $20$ $c{m}^3$. If the density of water is $1$g $c{m}^{-3}$, will the substance float or sink in water?

Answer 1

Given, mass of substance, $m=50g$;
volume, $V=20c{m}^3$; density, $\rho =?$

The density of substance given is

$d=\frac{m}{V}=\frac{50g}{20c{m}^3}=2.5gc{m}^{-3}$

Hence the density of the substance is greater than the density of water. Hence the weight acting downwards $Vdg$ is greater than the buoyant force acting upwards $V{\rho }_{water}g$.

Hence the substance will sink in water.