The setup is a flat friction surface where the ball rolls without slipping. Next, in one case it goes up a friction incline, and in the other a frictionless incline. Which ball leaves the incline faster? Both are given the same initial push. At the bottom of the incline both balls have the same energy and are rolling w.o slipping. But in the frictionless case the ball keeps spinning just as quickly as there is no torque. However, its center of mass slows down from gravity. In the friction case, does friction cause a torque? If so, then the center of mass slows down more. But if not, then gravity slows the balls center of mass velocity down just as much, and this acceleration from gravity also (because v=wr) slows the spinning down too. So it seems even if friction on the ramp doesn't slow the ball down, it ends with less energy. When I say which leaves faster, I mean which has greater center of mass velocity. Does friction on the ramp slow the center of mass velocity down? If not then both cases the center of mass is only accelerated by gravity so they end with the same final velocity, but one is spinning slower so their energies are different. Oh, I guess this means their final heights are different, the frictionless ramp ball must have a lower hieght as its rotational energy is greater and translation energy is the same. That is, if static friction on the ramp doesn't slow the center of mass velocity. I guess that's the main dilemma my problem comes down to. I remember that any force applied anywhere accelerates the center of mass as if it were applied to the center of mass, so I feel like friciton should slow transnational velocity, yet I've read that it doesn't. Please tell me what is wrong with that statement. I know there are other arguments like there is no displacement so no work, I get why those are right, but I dont understand why the statement "any force applied anywhere accelerates the center of mass as if it were applied to the center of mass, so friciton should slow transnational velocity" is incorrect. Thank you for any insight.