Question

A piece of ice floats in a vessel with water above which a layer of a lighter oil is poured. How will the level of the interface change after the whole of ice melts? What will be the change in the total level of liquid in the vessel?

Answer 1

Firstly,

$Density = \frac{Mass}{Volume}$

∵ The mass of the ice will remain the same before and after melting,

∴ $Mass = Density$ × $Volume$ ...(i)

Now, it is known that the density of water > density of ice

∴  Using Eqn. (i), it can be stated that part of ice which remains in the water (after melting) will result it greater volume of water than that of the ice; thus increasing the water level in the vessel.

We also know that, the density of light oil is < that density of ice

∴ Using Eqn. (i) it can be stated that the part of ice left in the oil will result in lesser volume of water; thus decreasing the level of oil  inside the vessel.