fullsizeoutput_4c6b Published March 31, 2018 at 1940 × 1484 in 3/26 – 3/30/18 (FBD, Newton’s 3rd) PhySP18SS6.1.10 From the Buoyancy Presentation: Archimedes Principle for Mercury (Hg). Hg has a density of about 13.6 g/ml (if I am remembering my chemistry) so it doesn’t take much volume of displaced Hg to equal the mass of the object.