I find it easiest to explain it in terms of electricity, which I assume most people here are familiar with. It acts just the same. Pressure, like voltage, is a

I find it easiest to explain it in terms of electricity, which I assume most people here are familiar with. It acts just the same. Pressure, like voltage, is a difference. The flow rate is like the current, how much goes though. A pipe has a resistance that depends on it's diameter and length. You can calculate the resistance of the pipe as the pressure difference over the pipe divided by the flow rate. One thing people might get confused by is why making the opening at the end of the pipe smaller makes the water go faster. What you do in electricity terms is add a series resistor, the total flow rate in the pipe will be lower, but the speed can be higher because it needs to go through smaller opening and so is more concentrated.