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Posers and Puzzles

Posers and Puzzles

  1. Standard member talzamir
    Art, not a Toil
    24 Oct '11 09:28
    A flagpole has diameter of 10 centimeters (4". A rope that is 10 meters (30' long has been attached to the top. It spirals around the flagpole 25 times before the other end of the rope reaches the ground. How tall is the flag pole?
  2. Standard member forkedknight
    Defend the Universe
    24 Oct '11 14:35 / 1 edit
    I get
    25 * sqrt(40^2 - 10pi^2) = ~619cm
  3. Standard member talzamir
    Art, not a Toil
    24 Oct '11 14:40
    I wonder why the answer I got is exactly 25 times yours..? And that does make the respectable-sized flagpole I had in mind..?
  4. 24 Oct '11 16:42 / 1 edit
    I agree with forkedknight's answer:
    sqrt[L^2 - (25*pi*d)^2]
    ,
    where L = length of rope and d = diameter.
  5. Standard member forkedknight
    Defend the Universe
    24 Oct '11 17:10 / 2 edits
    Originally posted by talzamir
    I wonder why the answer I got is exactly 25 times yours..? And that does make the respectable-sized flagpole I had in mind..?
    25 times what i got is 15x longer than your rope...

    *edit* I see your response was before I did my edit, and my edit added the multiplier of 25 that i missed in my initial calculation (I broke the flag pole up into 25 rectangles across which the rope makes the hypotenuse)
  6. Standard member talzamir
    Art, not a Toil
    24 Oct '11 17:58
    So we both multiplied by 25? That makes a very awesome flagpole. ^_^ So yes, a bit over six meters it is.