Question

A cubical block of wood of side of $10cm$ floats at the interface between oil and water as shown in figure with its lower face $2cm$ below the interface The density of oil is $0.6g/c{m}^3$ The mass of the block is

• A. $600g$
• B. $680g$
• C. $800g$
• D. $200g$

Answer 1

Answer: (B)

$680g$

Let the mass of the box be $M$.

As the box is in equilibrium, thus the weight of the box is balanced by the total buoyancy force.

$\therefore$ $Mg={\rho }_w(2\times 10\times 10)g+{\rho }_o(8\times 10\times 10)g$

OR $M=1\left(200\right)+0.6\left(800\right)g$

$⟹$ $M=680g$