1. The problem statement, all variables and given/known data Please see attachment. When θ = 0, mass m is at the bottom of the inclined plane. If I create a frame at origin O, with axes along the bottom of the plane and the dotted line (as shown in the picture), will my magnitude of the vector from O to A (along the dotted line) just be "l" (length of string)? 2. Relevant equations No equations 3. The attempt at a solution I feel like it is l + some other distance that I have no idea how to get. How I read the question is that the ball is at the edge of plane at θ=0, so that magnitude should be l + diameter of the mass. I'm not given any dimensions, or where point A is located. Is the magnitude just the length of the string and it's a poor drawing?