Which part of the iceberg displaces water equal in weight to the buoyant force? explain.

The iceberg has weight Wi = Mig and the buoyant force is equal to the weight of the displaced water, Ww = Mwg. Furthermore, since the iceberg is floating, its weight exactly balances the buoyant force:

Ww = Wi

Mwg = Mig

VwRhowg = ViRhoig

Vw = Rhoi/Rhow Vi

So, the fraction of ice underwater, Vw/Vi, is given by the ratio of densities Rhoi/Rhow=0.87. Over 87% of an iceberg's volume (and mass) is underwater. As you can see, the convenient definition of the gram gives us a quick way to see how much of a floating substance lies below the surface of fresh water: the fraction is equal to that substance's mass density in g/cm?.

Summary

Archimede's Principle of bouyancy states that the bouyant force on an object is equal to the weight of the fluid displaced by that object. The underwater fraction of a substance floating on water is given by that substance's mass density in g/cm3.