Physics will be affected anyway.
Correct me if I'm wrong, but it seems like you're trying to smoothly bring the ball back to a certain position while falling down.
I wouldn't try mixing Tween behavior with Physics behavior - it's just wrong.
To me, the best solution to this would seem to modify the velocityX of the Ball and you could do this every tick:
Replace 50 with your desired X position.
Don't mix Physics with anything!