设m2为m
对整体:
a=F/m1+m2)=F/(3m)
F推m1时,以m1为对象
F-N1=m1*a=2m*[F/(3m)]=(2/3)F
N1=F/3
F推m2时,以m2为对象
F-N2=m2*a=m*[F/(3m)]=F/3
N2=(2/3)F=2N1
即
N1=(1/2)N2
选A
设m2为m
对整体:
a=F/m1+m2)=F/(3m)
F推m1时,以m1为对象
F-N1=m1*a=2m*[F/(3m)]=(2/3)F
N1=F/3
F推m2时,以m2为对象
F-N2=m2*a=m*[F/(3m)]=F/3
N2=(2/3)F=2N1
即
N1=(1/2)N2
选A