So we are learning about fluid dynamics in my physics class right now, and while I "know" the concepts, I don't understand them. Bernoulli's law says that when a fluid flows from a large area to a smaller area, the pressure decreases and the speed of the fluid increases. I understand how the speed increases - the flow rate must remain constant (assuming an incompressible fluid). But the pressure decreasing seems counter intuitive to me. The ideal gas law states that decreasing the volume of a container increases the pressure. When a fluid moves from a larger diameter tube to a smaller one, why then does the pressure not increase as the ideal gas law would predict? I'm also confused about flow rates and energy. Say we have a vertical pipe with a constant diameter with water being pumped through it. The flow rate at the top and bottom are equal, and therefore the velocity of the water at the top is equal to that at the bottom. Yet this means the potential energy increases while the kinetic energy remains constant. How is this possible if energy is conserved? Bernoulli's law says that the pressure at the top will be less than at the bottom, so is pressure some sort of energy (indeed its units dictate that it's a measure of energy per volume)?