Hummingbird
One train leaves Los Angeles at 15mph heading for New York. Another train leaves from New York at 20mph heading for Los Angeles on the same track. The distance between LA and NY is about 5000 miles. If a bird, flying at 25mph, leaves from Los Angeles at the same time as the train and flies back and forth between the two trains until they collide, how far will the bird have traveled?
posted by Foobar @ 10:44 AM
4 Comments:
Say the train1(from LA) travels x distance => train2 travels 5000-x distance. Say they both travelled for time t before colliding.
speed = distance / time
x/15= 5000- x / 20
This gives you x distance , which is also the distance travelled by the bird.
why is that the bird travels x distance??
x/25= 5000/35
t = d/s
t = 5000/ (20 + 15) = 143
both trains meet after this time 143 units. the bird is flying all the while 143 hrs with 25mph.
D = t s =
143 X 25 = 3571.4 Miles
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