A Fly Caught Between Two Trains
Two trains, 200 km apart, are moving toward each other at the speed of 50 km/hour each. A fly takes off from the front of one train flying straight toward the other at the amazing speed of 75 km/hour. Once it reaches the other train, the fly bounces off it and flies back to the first train again at 75 km/hour. The fly repeats the trip until the trains collide and the bug is squashed.
What distance has the fly traveled until its death?
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The two trains will collide at the middle of 200 km, 100 km away from each starting point. So the distance traveled by each train is 100 km. So the time elapsed until they collide is
t = d/v = 100\50 = 2 hours
The total distance traveled by the fly is
d = Vt = 75 x 2 = 150 km