I wanted to inquire as to a thought I have on a situation with buoyancy and air pressure. In the first slide (slide 1), I am showing a situation where a buoyant object is pushing up on a support wall through a fixed wall that has water in it. Here are the factors: 1. The net buoyant force of the hollow object is 500 N (pushing upward) 2. The support structure is 300N in weight (purple) 3. The support structure is flush up against the inside of the horizontal walls and do not allow passage of water down 4. The friction is 50N (walls against the support structure horizontal wall; the vertical pole through the bottom fixed wall (grey) My query is... would this buoyant push from the water below be able to push the water up and out to spill over the sides and back into the main body of water leaving the area below empty with just air? I was thinking it would not need the air pipe to allow air to come in and equalize the air pressure since the air is also pushing down on all the water? But I am wrong? I believe that only with the air pipe will the net force upward (500N up minus (300N + 50N) = 150 N --- would be able to push the water up and out leaving the empty space?