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Homework Help: Physics book problem

  1. Aug 4, 2011 #1
    1. The problem statement, all variables and given/known data

    A train travels 890 km from Berlin to Paris and then overshoots the end of the track by 10m.

    2. Relevant equations

    a.What is the %error in the total distance covered
    b.Is it correct to write the distance by the train as 890,010m?Explain.

    3. The attempt at a solution
    I got the answer for a. The book says that the answer for b is no. But im not sure why. Can someone help me with b.
  2. jcsd
  3. Aug 4, 2011 #2


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    have you ever read the headline in the news paper "65,000 attend football final" and thought that if only you had gone there would have been 65 001 people there! I don't think that would be true either, for the same sort of reason.
  4. Aug 4, 2011 #3
    for B., Since 1Km=1000m, Writing 890,000m can be considered because it is the same as 890km. There's nothing wrong in using any of the two.
  5. Aug 4, 2011 #4


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    At best, 890 km is specified to three significant figures, so to add another 10m really is insignificant. Berlin might actually be 890.2 km away anyway.
    There is a chance that the distance is supposed to be only 2 figure accuracy. Berlin might be 892 km away, but it is rounded to 890.

    And the football crowd of 65,000 was probably rounded to the nearest 1000 people!
  6. Aug 4, 2011 #5


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    Not to mention that neither the train nor Berlin are mathematical points. So how would one go about measuring the "distance" between the train and Berlin? Where in Berlin do you put one point of your measuring tape and where on the train do you put the other end?
  7. Aug 5, 2011 #6
    thanks a lot!!!!
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