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Posers and Puzzles

Posers and Puzzles

  1. Standard member talzamir
    Art, not a Toil
    27 Oct '11 23:45
    A drinking glass has a round base with radius r1, height of h and radius r2 > r1 at the upper rim. On its side on the table the glass goes around in a circle. How many full rotations does the glass do during one such circle?
  2. 28 Oct '11 04:55 / 1 edit
    I get {[h^2 + (r2-r1)^2]^(1/2)}/(r2-r1).
  3. Subscriber joe shmo On Vacation
    Strange Egg
    28 Oct '11 05:03 / 1 edit
    Originally posted by talzamir
    A drinking glass has a round base with radius r1, height of h and radius r2 > r1 at the upper rim. On its side on the table the glass goes around in a circle. How many full rotations does the glass do during one such circle?
    I'll say

    Theta = 2*pi*(r2-r1)/h

    Theta = 2*pi

    so number of rotations is

    N = (r2-r1)/h
  4. 28 Oct '11 05:37
    Originally posted by joe shmo
    I'll say

    Theta = 2*pi*(r2-r1)/h

    Theta = 2*pi

    so number of rotations is

    N = (r2-r1)/h
    I do not think your answer will yield the right trends with respect to parameter variations. For example, consider if (r2-r1) becomes very small (for some constant h). N should get very big because the glass will sweep out a very large circle, right?
  5. Subscriber joe shmo On Vacation
    Strange Egg
    28 Oct '11 05:50
    Originally posted by LemonJello
    I do not think your answer will yield the right trends with respect to parameter variations. For example, consider if (r2-r1) becomes very small (for some constant h). N should get very big because the glass will sweep out a very large circle, right?
    yeah...I suppose so. I did it hastily while I'm slightly under the influence...sorry