Question

When an object floats on water and on a liquid with different volumes inside the water and inside the liquid .

Is the buoyant force acted by the water and the liquid equal?

for eg - A body floats with 1/3rd of its volume outside the water and 3/4th of its volume outside the liquid . what will be the density of the liquid ? is the buoyant force acted by the different fluids equal?

Answer 1

The force of buoyancy is given as, F = Vρg, where V is the volume of the liquid displaced, ρ is the density of liquid and g is acceleration due to gravity. So the buoyant force exerted by the displaced fluids be same if the mass i.e. the product of V and ρ, displaced by the submerged object in the given fluid is same.

A body floats with 1/3rd of its volume outside the water, F_B = (2/3)Vρg.

While if the same body body floats with 3/4th of its volume outside the liquid, F'_B = (1/4)Vρ_lg , ρ_l be the density of the liquid.

Now since there is no correlation given between the two Buoyant forces so in this situation we cant find the density of the liquid.