I have a container that measures 1 cubic foot and is full of water. I have another empty container that is 4.5 feet higher than the empty container. The full container has a fluid outlet on the bottom, and an air inlet on the top. A hose (1 inch diameter, 4.5 feet long) connects the fluid outlet to the empty container. I want to know how much air I need to add to the full container to move all of the water out of the full container. I tried figuring this out, but my answer is clearly incorrect. I reasoned that since 1 pound of pressure is required to raise the water 2.31 feet, 2 pounds of pressure should be sufficient to accomplish the job. Next (based on this thread: https://www.physicsforums.com/threads/volume-and-pressure.87911/) I calculated that (assuming no temperature change) it would take 2/14.7*1=0.136 cubic ft. This does not make sense, as it would not even fill the container, let alone pressurize it.