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Length of a rod

  1. Dec 6, 2011 #1
    Can anyone tell me what will happen to a length og a rod if it is measured in a running train and why?
  2. jcsd
  3. Dec 6, 2011 #2


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    For all practical purposes, nothing will happen. Down around the 15th decimal place or so, WAY below our ability to measure it, the rod will be shorter than if the train were not moving. This is assuming that you are talking about a real train, on earth, not a thought experiment with the train moving at a relativistic speed.
  4. Dec 6, 2011 #3
    yup........I am talking about a real train and thanx..............but can u please tell me if not a realistic train say if train is moving at the 70% speed of light then what will happen
  5. Dec 6, 2011 #4


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    Well, both the rod and your measuring stick will shrink a bit but you won't notice it since they BOTH shrink.
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