Q. A vessel contains oil (density$0.8\ gcc^{- 1}$) over mercury (density$13.6\ gcc^{- 1}$). A homogeneous sphere floats with half its volume immersed in mercury and the other half in oil. The density of the material of the sphere in $gcc^{- 1}$ is

A) 3
B) 6.4
C) 7.2
D) 12.8
Explanation

(c) If $V$ is the volume of sphere and $\rho$ is its density then
$V\ \rho = (V/2) \times 0.8 + (V/2) \times 13.6$
$= 7.2\ V$
Or $\rho = 7.2\ gcc^{- 1}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.