设前2米所用时间t1,则前3米所用时间为t1+t3=t1+32=1/2at1^23=1/2a(t1+3)^2两式相除得：2/3=[t1/(t1+3)]^2(t1+3)/t1=根号(3/2)1+3/t1=根号(3/2)t1=3(根号6-2)a=2*2/t1^2=4/[3(根号6-2)]^2=2(5+2根号6)/9前四米所用时...