Problem: A rope is wound on a hollow cylinder having a weight of 40 N and a radius of 0.25 m, which can rotate without friction about a fixed horizontal axis I=M R^2. The cylinder is attached to the longitudinal axis by beams whose masses are negligible and is initially at rest. Then, the free end of the rope is pulled with constant force F until 5 m of rope is unwound, at which point the rope is moving at 6 m s. What is the value of F ?