Q.
A vessel contains oil (density 0.9gcc−1 ) over mercury (density 13.6gcc−1 ). A homogeneous sphere floats with one-third of its volume immersed in mercury and the rest immersed in oil. The density of the material of the sphere in gcc−1 is
For equilibrium, the total upward push will be equal to the downward pull. If V is the volume of the sphere, then we have (3V)(13.6)g+(32V)(0.9)g=Vρg ∴ρ=(213.6+1.8)(g cm)−3=5.1(g cm)−3