[问答题]
A large spool of rope rolls on the g 05e;qck whk1aj3l (p,*xovkground with the end of the rope lying zd s:: jrjc6k;oyle/:on the top edge of the spool. A person grabs the end of the rope and walks a distance L, holding onto it, Fig. 8–50. The spool rolls behinjzsc:d;y r j6::olk/e d the person without slipping. What length of rope unwinds from the spool? How far does the spool’s center of mass move?