1.首先水平位移固定
x1=4.5m/s * 0.8s = 3.6m
则竖直位移为
x2=6sin(cos^-1 3.6/6)=4.8m
0.8s后前一个球的竖直速度和竖直位移
vy = at = 9.8m/s * 0.8s = 7.84m/s ,xy1 = at^2/2 = 3.136m
两次跑出后加速度造成的位移不变,所以
(4.8m-3.136m)/7.84m/s+0.8s=1.01s
即跑出后1.01s后拉直
2.A球水平位移为：
x=vt = 4.5*1.01 = 4.545m
A球竖直位移为：
y=at^2/2 = 9.8*1.01*1.01/2 = 5m
A球位移为：
根号（xx+yy）= 6.76m