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Simple conceptual and calculation relativity

  1. Sep 22, 2010 #1
    1. The problem statement, all variables and given/known data

    you are flying your personal rocket craft at v=o.9c from star A to star B. The distance between the stars, in the stars' reference frame is 1.0ly, bother star happens to explode simultaneously in your reference frame at the instance you are exactly halfway between them.
    do you see the flash simultaneously? if you do explain how. If you do not, which do you see first and what is the time difference the two flash.

    2. Relevant equations

    umm sure non needed.

    3. The attempt at a solution

    well ik that star B explodes first in rocket frame then star B explodes.(i know the explanation)

    im having a hard time finding the time difference!... if some one can give me a hint to approaching the problem it would be good!
    Last edited: Sep 22, 2010
  2. jcsd
  3. Sep 22, 2010 #2
  4. Sep 23, 2010 #3
    i am trying my best, it would really be helpfull if someone would help me please and thank you.
  5. Sep 23, 2010 #4
    Why do you have to go from rocket's frame to the star's frame and then go back to the rocket's frame? If the question asks something about the observation in the rocket's frame, it's better to consider the situation in the rocket's frame.
    In this frame, you see that when you're right in the middle of the stars, they explode. Then there is "flash". What is this "flash"? What is the flash's speed? From the fact that you're half way between the stars, can you deduce the distance that each flash has to travel to reach you? How is each distance of each flash compared to the other? :smile:
  6. Sep 23, 2010 #5


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    What's your explanation for the relative timing of the flashes? (@seto6)

    I second hikaru1221's suggestion of looking at the event in the rocket's frame.
  7. Sep 23, 2010 #6
    the stars do explode at the same time in rocket frame but since the person in the rocket is moving towards star B, the person in the rocket will see the star B explode first then star A exploding. there is a delay between the explosion
  8. Sep 23, 2010 #7


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    In the rocket's frame, what is the motion of the person in the rocket?
  9. Sep 24, 2010 #8
    i see rockets frame is persons frame there for explode at same time so...change in t =0 correct?
  10. Sep 25, 2010 #9


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    If I understand you correctly, yes, that's correct.
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