(1)η=W有/W总=GH/FS=G/2F得F=100N
G轮=2F-G=2X100N-100N=100N
(2)η=G/(G+G轮)=900N/(900N+100N)=90%
(3)由η=G/(G+G轮)得当η=80%时,G=400N
F=(G+G轮)/2=500N/2=250N
(1)η=W有/W总=GH/FS=G/2F得F=100N
G轮=2F-G=2X100N-100N=100N
(2)η=G/(G+G轮)=900N/(900N+100N)=90%
(3)由η=G/(G+G轮)得当η=80%时,G=400N
F=(G+G轮)/2=500N/2=250N