If I have a cylinder rolling down a slope, the friction would point towards UP the slope, right? So if instead the cylinder was _pulled_ up the slope by a force, wouldn't the friction direction be down? I have a problem because I have two separate lecture notes which state different answers and I don't know which of them is right. One says the friction would point up (which I think is wrong) and the other one says down. Also, it's confusing because physics books say that friction always opposites movement. But if the cylinder is rolling on a plane, say, right, then the rotating movement would be clockwise. Why isn't the friction then opposing that rotating movement so that the friction force would be pointing right also? I mean, the lowest point of the cylinder is always moving left. Secondly, if you put a rolling cylinder that's in the air (also rotating clockwise for example) to a plane and it starts to _slide_ at first, which way would the friction be at that case? I've been searching the net and physics books for hours and I can't make these questions clear to myself, please help!