I am designing an air pressure cannon, that relies on a tank of compressed air to drive a projectile through, and eventually out of, a tube. The initial acceleration (when the projectile is at the start of the tube) will be greater than the final acceleration (when the projectile has reached the outlet end of the tube). How can I calculate the velocity of the projectile, when the acceleration is changing? This is a problem where the acceleration changes, based on distance covered by the projctile, not based on change in time. Thanks!