Rigibody2D.AddForce within a scaled GameObject

Hi, i'm adding a force to my player (Rigidbody2D). This player is inside a scaled GameObject (0.5,0.5.0.5). This is the basic setup to display the content on an iPhone. If i run the game on an iPhone 6+ / iPad Retina i scale the GameObject to 1,1,1 to match the bigger screen size. But the force applied to the player is not the same. In order to compensate the scale i thought i could just double the force applied to the player but that does not match the experience on the iPhone (which needs to be exactly the same). Question: Does the amount of force needed to move an object within a scaled GameObject change with the scale of the parent and if so why isn't it 1:1?