A body is rolling without slipping. Let P be topmost point at an instant and Q bottom-most point at that instant..Is it true that Q remains stationary with respect to P all the time? What i thought was the purely mathematical thing. P will have velocity 2v to right and Q will have 0 velocity. Velcoity of Q with respect to P comes out to be -2v. BUt thinking about it, P is always at a distance of 2r from Q. So i am confused as to what should be answer?