设距离为X则X=1/2gt^2=5t^2X-1.4=1/2g(t-0.2)^2=5(t-0.2)^25t^2-1.4=5(t^2-0.4t+0.04)=5t^2-2t+0.22t=1.6t=0.8X=5t^2=3.2m
h=1/2gt^2h-1.4=1/2g(t-0.2)^2g=10联立求解得：t=0.8sh=3.2m
1.4=v1t at方/2,求v1，h=v1方/2a
