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Light speed

  1. Aug 31, 2013 #1
    Lets say we run(forever) with 200km/h and our friend with 10km/h.
    Time will run slower for me or will run faster for my friend???
     
  2. jcsd
  3. Aug 31, 2013 #2

    Doc Al

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    Staff: Mentor

    Those speeds are with respect to what? For example: You run eastward at 200 km/h with respect to the ground and your friend runs westward at 10 km/h with respect to the ground.

    "Time" is relative. You think your clocks (and everything else moving along with you) are running at their normal rates. But you say that your friends clocks are running slow compared to yours.

    Of course, it's completely symmetrical. Your friend says the same thing about your clocks running slow.
     
  4. Aug 31, 2013 #3
    If I run faster I will see my friends clock go slower,and my friend will see my clock to go faster?
     
  5. Aug 31, 2013 #4

    Doc Al

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    No. You both see each others clocks as running slow.
     
  6. Aug 31, 2013 #5
    Ohh why? I thought the faster you run the slower time.
    Why the slower person see the time of faster person with slower from his time?
     
  7. Aug 31, 2013 #6

    Doc Al

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    Only as seen by someone else, not by you. As far as you are concerned, your clocks run normally.

    Time dilation is one of the consequences of relativity. It is derived, like everything else, from Einstein's postulates: the laws of physics are the same in every inertial frame and the speed of light is the same in every inertial frame.

    Since you're obviously interested in relativity, I recommend you get yourself a good tutorial book and work through it, step by step.
     
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