@kailmenoke Cannonballs, cars, the physics are the same even if the magnitudes are different.
In talking about softballs and cannonballs, the physics of their trajectories are identical. You apply an initial force and they follow a parabolic trajectory assuming a gravitational field. When you are launching from a stationary position, you only need to consider force components in two directions, one vertical and the other horizontal.
Now when you start moving, then things become more complicated. Now you have to consider motion in the x-z plane in addition to your parabola. Neat stuff in my opinion.
But I'll have to test this vigorously when I play next. Based on physics, velocity in the x-z plane of motion is essentially constant. That means that if you are traveling at constant speed and fire the cannon and you are shooting perpendicular from the side of the vessel, the cannonball shouldn't move at all to the left or the right of the cannon. It should only appear to go up and then back down again.
I guess it is time to pick at the physics engine here...