Archimedes' Principle: The buoyant force on a submerged object is equal to the weight of the volume of the liquid displaced: FB = PLVg, where FB is the buoyant force, PL is the density of the liquid (not the density of the submerged object!), and V is the volume of the liquid displaced. Since (PLV) is the mass of the displaced liquid, then (PLVg) is the weight of the displaced liquid.
A wooden cube with a side of 10 cm is floating on the surface of the water. The density of wood is 0.75 g/cm3 and the density of water is 1 g/cm3. Is the cube floating completely submerged in water or only partially? If only partially, what percentage of the volume is submerged? (Draw a free body diagram of the block)
If a cube of unknown material sinks completely and falls to the bottom of the water, draw a free body diagram. Can we find out the density of the block from only knowing that it sinks?