Hello, I noticed something odd today while removing two identical tubs of cottage cheese from the fridge. They were stacked one on top of the other with no visual way to tell if a container was half full or completely full. When picking them up at the same time by only grasping "the lid of the bottom container," I felt that the bottom tub was more full than the tub on top. When I checked I found that I was right. I decided to put the half full tub on the bottom and tried picking them up together again... only by grasping the lid of the bottom container. I could tell immediately that the tub on the bottom was lighter. What was confusing wasn't how I was able to tell which tub was more full than the other with the two experiments, but why the total weight of the two tubs held together seemed lighter when the half full tub was on the bottom. I could have held it indefinitely without support. While when the heavy tub was on the bottom, it honestly felt as if I needed to eventually support my wrist. Disregarding that it was merely psychological ...what would explain the total weight of both tubs seeming lighter only when holding the half full tub on the bottom?