(1) 设A的速度为v,B为5v
4(v + 5v) = 15
v = 5/8
4s后:AO = 4*5/8 = 5/2,A(-5/2,0)
OB = 4*5*5/8 = 25/2,B(25/2,0)
(2) 再过秒,A(-5/2 -5t/8,0),B(25/2 - 25t/8,0)
原点恰好处在两个动点的正中间:-(-5/2 -5t/8) = 25/2 - 25t/8
t = 8/3
(1) 设A的速度为v,B为5v
4(v + 5v) = 15
v = 5/8
4s后:AO = 4*5/8 = 5/2,A(-5/2,0)
OB = 4*5*5/8 = 25/2,B(25/2,0)
(2) 再过秒,A(-5/2 -5t/8,0),B(25/2 - 25t/8,0)
原点恰好处在两个动点的正中间:-(-5/2 -5t/8) = 25/2 - 25t/8
t = 8/3