This calculator was created by user's request. He needs to find a weight of body in liquid. Here comes the Archimedes' principle: The buoyant force on a submerged object is equal to the weight of the liquid displaced by the object.
So, from one side the body in liquid is affected by gravity force, which is or . From the other side the body in liquid is affected by buoyant force. Now everything depends on body's density. If it is greater than liquid density, the body will drown, if not - it will be pushed out of liquid until two forces will become equal (The buoyant force become less as body come up out of liquid). The part in the water will be proportional to the liquid/body densities ratio.
The difference between actual weight and apparent weight will be equal to the weight of the liquid which was displaced, and it is volume of body under water multiplied by liquid density.