1. The problem statement, all variables and given/known data There is a string of length L dropped through a spool of thread. 10 paper clips are tied to each end and one end is twirled so that one bunch of clips moves in a horizontal circle at speed v while the other hangs vertically. Neglecting friction, write an expression: a) for the distance d as a function of v and L, where L = r + d (r = radius) b) for g in terms of v and r, the radius of the circle. 2. Relevant equations a(c) = v^2 / r 3. The attempt at a solution I don't even know where to begin. Since L is already given, d is obviously L - r. I've tried to re-arrange the centripetal acceleration equation to get r = v^2 / a, but that still introduces a. I then took the regular velocity v = 2pi*r / t but rearranging that for r will still give v*t. What am I missing?