String is wrapped around an object of mass M and moment of inertia I. With your hand you pull the string straight up with some constant force F such that the center of the object does not move up or...

String is wrapped around an object of mass M and moment of inertia I. With your hand you pull the string straight up with some constant force F such that the center of the object does not move up or down, but the object spins faster and faster (Figure 11.109). This is like a yo-yo; nothing but the vertical string touches the object.