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Which Latitude has the Smallest Radius?

  1. Aug 31, 2012 #1
    °1. The problem statement, all variables and given/known data

    I need to find which latitude has the smallest radius.

    40°30'13" or 30°40'13"

    2. Relevant equations


    3. The attempt at a solution

    I converted from DMS to degree and got:

    40°30'13" ≈ 40.72° and 30°40'13" ≈ 30.88°

    Since the Earth is not a perfect sphere, I said that 40°30'13" has the smallest radius because it is farthest to the equater, meaning the farther you are to the equater, the smaller the radius.

    I don't know if I did this right because I think it is means that each latitude has it's own circle, but I don't know how to get circles from latitudes.

    Am I correct in my assumption that 40°30'13" is smaller because it is farther from the the equater?

    *Knowing that at 0° the distance to the equater is greatest because of the elliptical form*
    Last edited: Aug 31, 2012
  2. jcsd
  3. Sep 1, 2012 #2


    Staff: Mentor

    On a globe of the earth, the latitudes are circles that are "parallel," and run east and west The longitudinal meridians run north and south and are also circles that intersect at the north and south poles.

    The farther the latitude is from the equator, the smaller the circle, and hence, the smaller its radius.
  4. Sep 1, 2012 #3
    Just for clarification, the equator is at 0° so the 40°30'13" has a smaller radius because it has a greater degree then 30°40'13"?
  5. Sep 1, 2012 #4


    User Avatar

    Staff: Mentor

    I had to look it up:


    So yes, the equator is 0 degrees, and the + direction goes north, and the - latitude direction goes south. Good job!
    Last edited: Sep 2, 2012
  6. Sep 1, 2012 #5
    Ok, thanks!
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