Posers and Puzzles

Posers and Puzzles

A Helical Hassle!

Standard memberRemoved
Posers and Puzzles 07 May '21 01:12
  1. R
    Standard memberRemoved
    Joined
    10 Dec '06
    Moves
    8528
    07 May '21 01:121 edit
    A string is wound symmetrically around a circular rod ( common helix ). The string goes exactly š‘› times around the rod and the rod has a circumference of š‘› and a length of 3š‘›

    Find the value of š‘› for which the length of the string is 20.

    Assumptions: neglect any dimension of the string itself.
  2. Standard memberBigDogg
    Secret RHP coder
    on the payroll
    Joined
    26 Nov '04
    Moves
    155080
    10 May '21 03:29
    @joe-shmo
    Reveal Hidden Content
    Basically, we are solving a right triangle of hypotenuse 20 and other sides n and 3n. 9n^2 + n^2 = 400; n^2 = 40; n = 2 sqrt 10
  3. R
    Standard memberRemoved
    Joined
    10 Dec '06
    Moves
    8528
    10 May '21 11:20
    @BigDoggProblem

    On the right track. š‘› is an integer

    Still open.
  4. Standard memberBigDogg
    Secret RHP coder
    on the payroll
    Joined
    26 Nov '04
    Moves
    155080
    10 May '21 18:20
    @joe-shmo
    Reveal Hidden Content
    I think I have it now. Starting equation is nā“ + 9n^2 = 400. Solving for n, I get n=4.
  5. R
    Standard memberRemoved
    Joined
    10 Dec '06
    Moves
    8528
    10 May '21 18:23
    @BigDoggProblem

    Now you got it!
Back to Top
Sign up or Connect to Play Chess

Cookies help us deliver our Services. By using our Services or clicking I agree, you agree to our use of cookies. Learn More.I Agree