I'm not sure how to post a figure, but think of a glass full of water that gets tipped on its side. The pressure at the interface is equal to atmospheric pressure in both fluids (water and air), and yet the water flows out of the glass and is replaced by air. What's the explanation? How long...
Related problem
I have a closely related question: I have a horizontal pipe open at one end filled with a high density fluid. The open end is connected to a large reservoir containing a lower density fluid. Both fluids are at the same pressure. How can I calculate the time it takes for the high...