1. The problem statement, all variables and given/known data A yo-yo is spun from rest by pulling on the string with a constant tension of 2.0 N. The radius of the inner rod on which the string is strung round is 0.50 cm. The tension is applied for 5.0 seconds after which the yo-yo is observed to spin with an angular velocity of 15 rad/sec. a)What is the moment of inertia of the yo-yo? b)What is the total angle the yo-yo has traveled through in these 5 seconds? 2. Relevant equations Moment of Inertia of hollow cylinder: I= 1/2*m*(r1^2+r2^2) 3. The attempt at a solution For a) I know the moment of inertia of the yo-yo (hollow cylinder) is 1/2*m*(r1^2+r2^2). We are given the inner radius, but I have no idea how to find the outer radius. I know how to find the mass since we know the tension and we can work backwards. For b) I don't even get what the problem means? Any help appreciated! Thanks!