> Sure. I'll set the problem up, and you can finish it. > Pick one of the trains as you reference point, and draw > the graphs T(t), and f(t). T(t) is the train's distance from you > versus time, and f(t) is the fly's versus time. Find the distance > the fly travels in the first cycle, from your train to the other > and back to you, call it D1. Because of the constant speeds in > the problem, the graphs of T(t) is a negative-sloped line from > (0,T(0)) to (tf,0). The graph of f(t) is an infinite series > of similar triangles. From the parameters of the problem you can > find a proportionality constant that relates > the distance of the second cycle, D2, to D1. D2=cD1. > So the total distance the fly travels is sum(n=1,oo)D1*c^n.
Yes, I have managed to solve it. It is simple:
s1*SUM(C^n,n=1,oo) where C = V1/V2 (If you have one train as a refernece point)