I understand the concept of this question, I think, but I don't know how to go about getting an answer. A tank is completely full of water with no air. A valve at the bottom is opened, while one on top remains closed. What is the lowest pressure that the tank will reach. From valve to valve the height is 30ft. I understand that as the water drains, it will pull a vacuum inside the tank, which will eventually collapse at a low enough pressure. I also know that the water will vaporize at some point due to the lack of pressure in the tank, but I don't know if they want the vapor pressure (no temp was given) or if there is some calculation to do. Any guidance is appreciated!