When you say "force", I assume that means you're using the physics behaviour? You should never combine physics with any other movement behaviour, as they have conflicting effects on the object.
But, I was in the mood to do a simple cannon game using physics, so here you go. This should be more than enough to get you started.
Up/down/left/right to adjust angle and power; spacebar to launch. Pay particular attention to the physics properties of the ball, such as density, friction and angular damping.