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Two trains are on the same railroad track separated by 200 miles and facing towa

ID: 2889665 • Letter: T

Question

Two trains are on the same railroad track separated by 200 miles and facing towards each other. Train A is moving at 50 mph while Train B is moving at 100 miles per hour. At that instant a very fast flying bird that flies at a rate of 125 mph takes off from the tip of Train A and flies directly towards Train B, which it just reaches, then turns around instantly and flies back towards Train A, then turns around upon reaching Train A and flies back to Train B, repeating this process until the two trains collide. How far does the bird fly in total?

Explanation / Answer

speed of bird = 125 mph

speed of train A v1 = 50 mph

speed of train B v2 = 100 mph

Distance between train A and B = 200 miles

relative velocity = 50+100 =150 mph (because both are in opposite direction)

Time taken by trains when collide t = d/v =200/150 = 4/3 hr

So distance travelled by bird = ( speed of bird)* t

= 125*4/3 =500/3 =133.33 miles