# 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, the bird flies directly back to the first train, and so forth. (We have no idea why a bird would behave in this way.) What is the total distance the bird travels before the trains collide?

1
by evilcat

2015-05-29T17:01:58+05:30
Given ;-

Speed of the two trains when they are headed in the same track = 30 km / hr

Speed of the bird when it flies off the front of one train = 60 km / hr

To find ;-

⇒ What is the total distance the bird travels before the trains collide?

Sol ;-

Let us take the speed of one train as V₁ and the speed of another train as V₂

Now, Let us take the total distance between the to trains as  - x = 60 km

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⇒ Time taken to collide each other =  ( V 1  +  V 2 )   / X

=   ( 30    +  30 )    / 60

=       60    /   60

= 60 min                = 1 hr

Time taken to collide each other = 1 hr

Time taken for the Bird Flight is = 1 hr

Now let us find the total distance by the bird -

Total distance travelled by the bird     =  Speed of the bird × Time of the birds   before the trains collide                                                             flight

=  60  × 1 = 60 km

So ,  total distance of the                       =  60 km
bird  before the trains collides