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Apply the concept of relative velocity

  1. Feb 1, 2007 #1
    I cannot understand how to apply the concept of relative velocity in certaijn questions like the below one
    the question is Two trains A and B of length 400m each are moving on two parallel tracks with a uniform speed of 72km/hr in the same direction with A ahead of B The driver of B decides to overtake A and accelerates byt 1m/s2 If after 50s the guard of B just brushes past the driver of A, what was the original distance between them?
    sir, I know that train B's acceleration is 1m/s^2 time is 50s initial velocity is O and by equations of motion we can find the distance. But my teacher said here the concept of relative velocity comes into play. Please explain me why and how?
    Last edited: Feb 2, 2007
  2. jcsd
  3. Feb 2, 2007 #2

    Gib Z

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    Homework Helper

    This shouldn't be in the Tutorials section. This section is for knowledgeable people to post tutorials.

    To your question,

    We can take them to both be going at v=0 yes? Relative to each other.

    O btw, a is constant, 1, we can use the equations now. s=ut + (at^2)/2. Let a=1 and make other relavent substitutions.

    Moderator, move this thread please.

    Edit: I just realised i sounded really cold in that post, no disrespect winnie3, hope u have fun here at physicsforums.com :)
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