Three identical glasses are filled to the same height with water. The first glass is filled with water only(Wa). The second glass has an object of volume V and density half that of water floating in it (Wb). The third glass has an object of volume V and density twice that of water on the bottom of it (Wc). All three glasses are sitting on scales. Compare the weight of each of the glasses: Wa, Wb, Wc.

Answer 1

Let
mass of water in Wa = Ma
mass of glass = Mg

a) mass = Ma+Mg

b) mass = Ma + Mg - ρV + ρV = Ma + Mg

c) mass = Ma + Mg + ρV - V = Ma + Mg - (ρ-1)V