Greetings all. My son has asked me to help him build a small air cannon. He is very interested in the sciences, especially physics, and always wants to know as much as possible about things of that nature. The cannon we are building has the following specifications: It will be made out of sch 40 3 inch pressure rated PVC as follows: pressure chamber: 3" x 8" Barrel : 3" x 24" We plan on using approximately 40 psi in the chamber (or less) His questions to me, which I cannot answer simply because I have no idea, is the math behind the physics of the air cannon. Based on the dimensions and psi that I have provided, and assuming we will be shooting a tennis ball 2.7" diameter, can anyone explain, as simply as possible and show the formulas, for how we can derive initial velocity, final velocity, acceleration out of the barrel, etc. If I need to provide any other info please ask. I am totally lost when it comes to the math, but my son loves this stuff and really wants to understand how it will all work together. It is tough not being able to explain to your own child when he needs help. At least we will build it together and have fun doing that lol Thanks in advance for your kind help.