Alright, so I'm trying to design an air camber for a paintball marker. I know to get an approximation for the volume I can use energy equations. I'm using: KE1 + PE1 = KE2 + PE2 and KE = .5mv^2 PE = pressure(volume) I want an initial pressure of 150 psi, and a final velocity of 290 feet per second. A paintball's mass is approximatly 3.19 grams or 0.007 lb. I set up an equation like this: (150 lb/in^2)(X)=(.5)(0.007lb)(3480 in/s)^2 A friend said it was 6.4 in^3, but I can't see what he did. I don't know if I've just done conversions wrong, set up the problem wrong, or what.