Wow. I'm blown away. As a chemical engineer by training my gut was saying conservation of energy, but my sons kept entertaining ideas of the constriction and flow and that was showing some insight that I couldn't put my finger on. The ram pump and your explanation about flow and pressure...
As our family drove along the highway, one of my 3 college boys started commenting about the water towers we were seeing. We started a deep discussion about how water towers work and that led to a fascinating discussion about water supply in skyscrapers that are clearly taller than your average...