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Homework Help: Time space diagram

  1. Apr 26, 2008 #1
    i attached the diagram.

    a) the object whose world line is labeled B is moving along the x-axis T or F?

    I said false because yes while it is moving along the x axis it's also moving along the y-axis. So it's moving in two dimensions not just one. is my answer and reasoning correct?



    The world line for object E (a completely horizontal world line) cannot possibly be correct right? The reason behind this is because it has a slope of zero and it must have a slope of one or greater. Having a slope of 1 or less than one means that the object is traveling at the speed of light or faster than the speed of light which is not possible.
     

    Attached Files:

  2. jcsd
  3. Apr 26, 2008 #2

    Doc Al

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    Staff: Mentor

    No, your answer is incorrect. For one thing, the "y-axis" represents time. The spacetime diagram is just a picture representing where the object is as a function of time. World line B shows an object moving left and then right along the x-axis.
    Right! (Assuming you are measuring both axes with comparable units--ct instead of just time.)
     
  4. Apr 26, 2008 #3
    for the first portion.

    if the object is moving left then right along the right-axis then what is the difference of an object that is moving in a curved manner like B and an object that would move in a staright manner like A
     

    Attached Files:

  5. Apr 27, 2008 #4

    Doc Al

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    Staff: Mentor

    While the worldline of B might be curved, both A and B are moving in a straight line. They both only move back and forth along the x-axis. The difference is that A moves with constant speed to the left then instantly reverses direction and moves with constant speed to the right while B slows down and reverses direction more gently.
     
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