[问答题]
A large spool of roplf l 4) :k:grzae*jo *o4lt0jh rl+gszr8fu8 5e rolls on the ground with the end of the rope lying on the top edge of the spool. A person grabs the end of the rope and walks a distance L, holding onto r85furg lz+s8 it, Fig. 8–50. The spool rolls behind the person without slipping. What length of rope unwinds from the spool? How far does the spool’s center of mass move?