[问答题]
A large spool of rope r)6cx / 9spinjsd8yrv5olls on the gro mr+ pqdhru1 )s7(dymqn/o 03lund 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 it, Fig. 8–50. The spool rolls behind the person without slipping. What length of rope unwinds frol d ousm(dh1p7r/q)3q rym 0n+m the spool? How far does the spool’s center of mass move?