The best riddles. Anywhere.
Two Trains And A Bird
posted by Caprico - April 12 2011 09:02:02 AM
Two trains, A and B are approaching each other with a constant velocity of 60km/hr. The initial distance between them was 120km. At that initial instant, a bird from train A started to fly towards train B with a velocity of 240km/hr. As soon as it touched B, it turned and flew towards A. As soon as it touched A, it turned again. It kept doing this till the trains collided.

Q1) How many such trips does the bird make till the trains collide?
Q2) What is the total distance traveled by the bird?

Before applying science or mathematics, try applying pure logic. Use the "hide" feature please if you know the answer. [I know it is unbelievable for the bird to travel faster than the trains, but just go with it. Assume, its a super-bird]
Reply by Ragib - April 12 2011 11:02:45 AM
total distance of 240 kilometres.will it travel infinite number of times?i am not sure.

Reply by budunk - April 12 2011 11:14:39 AM
[hide]It takes 1 hour before the trains collide since each travel 60km in one hour.

In this time, a bird going 240km/hr can travel 240km. That answers the second question.

The bird, though, would make an infinite number of trips to travel that distance as the trains get closer together (if you break the problem down into limits and the limits are going to infinity.)
[/hide]

Reply by Ragib - April 12 2011 11:18:33 AM
hm,i was right.

Reply by Caprico - April 12 2011 11:46:30 AM
Yup, both you guys are right... Well done... :) Ragib, stop sitting on BigRiddles and go study for your boards! :P

Reply by Ragib - April 12 2011 12:45:41 PM
i have got 4 days gap before physics exam.i am not so studious.he he