posted by Sadia on .
Two trains, each having a speed of 30 km/h, are headed at each other on the same straight track. A bird that can fly 60 km/h flies off the front of one train when they are 60 km apart and heads directly for the other train. On reaching the other train, it flies directly back to the first train, and so forth. What is the total distance the bird travels?
Best to draw a timeline with a diagram for each key moment in time. Let us know if you get stuck.
How long before the trains meet? How long is the bird in the air? How far can the bird fly in that time?
The bird is traveling for an hour because it takes the two trains 60 minutes to travel 30 km to the point of collision. Since the bird has been flying for 60 minutes and it traveles 1 km per minute, (60 min) * (1 km / min) = 60 km