Throw an object following a curve in 2D

Hello, I am trying to create a pong template, with the twist of being able to curve the ball with the paddle. Imagine this classic game: http://www.curveball-game.com but in 2D. Everything in my scene is kinematic, except for the ball, so when the scene starts, I addForce to the ball's rigid body and it bounces on the bounds and paddle. In order to calculate how big the curve should be, I am saving the last 10 values of the paddle's position inside fixedUpdate. Therefore, at the moment of the impact I know how fast the paddle was moving and apply an appropriate curve. This is where my question starts. In my first implementation, I am using AddRelativeForce inside the ball's FixedUpdate, pointing to the left or the right (depending on the paddle's direction during the impact), in order to simulate a curve. But this constant force is messing with the ball's velocity, meaning I am experiencing an acceleration every time I am curving the ball. I want to be able to control the maximum velocity of the ball at any time. Should I abandon the addRelativeForce solution? What is the best way to achieve this behavior? Thanks!