(2) M-Ja-FR F= Ja 5.6×102×1.26×102_47N R 0.15 A-MO-FRO =47×0.15×5=111J 结束目录= = a F R J = 5.6×10-2×1.26×102 0.15 47N A =Mq =FRq =47×0.15×5π=111J (2) M= J a =FR 结束 目录