对m:F-u1mg=ma1得a1=3m/s^2对M：u1mg-u2(M+m)g=Ma2得a2=1m/s^2s1=a1t^2/2s2=a2t^2/2s1-s2=1得t=1s故木板的位移s2=a2t^2/2=0.5m
