Here's one for you -
The theoretical maximum speed the ball could leave the robot is twice the speed that the kicker strikes it at.
Example: Throw a tennis ball at a wall. It hits the wall, and leaves with the same speed that it came in with. Now imagine this is in space, and the wall has near infinite mass. Also, the tennis ball isn't moving, but the wall is. Same scenario, and the same results.
A better way to go about this is trying to figure out how far and at what angle you want to kick the ball. After having those constraints, you can then figure out the velocity at which the kicker needs to have when it strikes the ball. Then, you can figure out the geometries and forces involved.
Oh, and then you can multiply everything by PI for good measure. Don't ask me why, ask yourself why not.
