Yeah, thanks for the responses. Coming to think about it, I feel the questions just 'feel' a tad easier since we generally do the passages after just having read the corresponding section.
I just looked at that problem. I'm assuming you're talking about #9, I also thought it was 0. But the solution does make sense, since in theory, the string should rotate around the hinge where it is attached to the wall. They should have been clearer I think - the problem makes it sound as if the rope is glued to the wall, but I think they meant for it to be a rotating hinge. (at least, based on their answer)