Demo

[Load Problem.]

  A big red yo-yo is going up and down at the end of a string. The outer radius of the yo-yo is 1 m and its mass is 2 kg. The string is wound around an inner "wheel" that has a certain radius. What is the radius of that wheel? (string position is not drawn to scale) You will need to find the tension in the string and the linear acceleration. Assume the yo-yo is a solid disk. If you can find the angular acceleration of the yo-yo, you should be able to determine the torque that the tension in the string exerts. This in turn should allow you to determine the radius of the inner "wheel."