t=2时:20=Vo*2+(1/2)a*(2*2)=2Vo+2at=-2时:12=Vo*(-2)+(1/2)a*(-2)*(-2)=-2Vo+2a联立，解得a=8m/s^2Vo=2m/st=1时S=Vo*t+(1/2)at^2=2*1+(1/2)*8*(1*1)=6m
