[问答题]
A large spool of rope rolls on the ground tzx kxh ) f319: cfv(.bavadj6with the end of t1v)b1,qmzbur i-2.wzx k:f ljhe rope lying on the top edge of the spool. A person grabs the end of the rope and walks a distance L, 1v.b:l qxm2rwf-uz kz 1j,)ibholding onto 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?