Akshully, the density plays its part becase of Archimedes force an atmosphere is applying to an object. The less dense an object is, the lighter it will weight for the same mass. E.g. the air baloon with helium inside will have a mass even higher that an empty one because of added helium mass, yet it may float up thus having a negative weight (in the atmosphere)
What the hell! Let's all just go crazy! (lemmy.world)