[SOLVED] Water guns Currently on a forum about water guns there is a debate going on about what determines a water gun's performance between pressure and force. On one side are people who say that higher pressure differentials combined with a higher "Cv value" will mean more flow, which translates into greater distances achieved. On the other side are those (mainly myself) who say that Newton's second law is clear and that force determines how much flow (movement) is created. The forum thread can be read here: http://forums.sscentral.org/t4243/ Now, I will admit that I am just a high school student. I've taken 3 physics classes and two calculus ones and I think I'm pretty good with basic physics. I've built many water guns, including a water gun designed explicitely to have extremely high force applied to the water by having high pressure in addition to a large area to apply the pressure. This water gun currently holds a record for distance shot and I'm working on one to shoot further with more force. Naturally, I'm on the side of force because it's reality as far as I'm seen. And the more I research it the more sure I am, especially after reading about the Navier-Stokes equations The pressure people's debate essentially states that the equation Q = Cv * sqrt(Pgauge) determines how much flow is created by a pressure. I'm not quite sure that equation is used for that purpose. I've tried to explain to these people that the Cv equation is meant to calculate flow lost through a valve in a simplified manner, but these people don't want to hear it. Can someone explain to me if this equation can be used to calculate flow created from a pressure differential and if it can not be used that way, can someone explain to me why this equation can not be used? My debate essentially comes down the Newton's second law applied to fluid dynamics. I've read pages that describe the Navier-Stokes equations for fluid flow that state movement (flow) is based upon force. I've brought these up with these people, but they ignore them. I don't have the time to get into all of the small debates involved, but the larger debate comes down to this. Who's right? In the next week I intend to build a water gun more powerful than the one I mentioned earlier and I feel this will show that force matters when it comes to water gun performance... but I would like to get the facts straight before then.