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Homework Help: Order of magnitude problems

  1. Sep 1, 2008 #1
    1. If the entire population of the United States forms a human chain by holding hands, how many times can such a chain be wrapped around the earth's equator. Round your answer to the nearest integer.

    2. There were no formulas given for this problem. I googled the length of the earth's equator: it is 6.37 *10^6m and I know that the United States has about 300 million people

    3.I tried multiplying 300 million with 6.37*10^6 and got the answer wrong. I'm completely desperate now; I don't have enough information to solve this problem
  2. jcsd
  3. Sep 1, 2008 #2


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    The length of Earth's equator is not 6.37*10^6. That is its radius. You need to multiply this by 2pi to get the circumferance.

    You might be able to space your people a little farther than 1 meter apart.
  4. Sep 1, 2008 #3


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    The point of this kind of problem isn't to google the data - it is to be able to find a way of estimating the values you need, at least to within a factor of a few.

    So the circumference of the earth. The metre was originally defined as 10,000,000 the distance form the equator to the North Pole, so the eath's circumference is about 40,000Km. If you didn't know this - what's the distance between say New York and LA, howmany time zones apart are they. Since there are obviously 24 timezones around the earth you can get the circumference.
  5. Sep 1, 2008 #4

    Vanadium 50

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    Why did you decide multiplying was the thing to do?
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