对物块μmg=ma1 a1=4m/s^2对小车
F-μmg=Ma2 a2=3m/s^22.v1=a1t v2=v0+a2t t=2s3. x1=1/2a1t^2+v1(t'-t)=16m4.Δs=v0t+1/2a2t^2-1/2a1t^2=2m