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  2. Helix - Wikipedia

    en.wikipedia.org/wiki/Helix

    The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. [3] A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. The slope of ...

  3. Pitch angle of a spiral - Wikipedia

    en.wikipedia.org/wiki/Pitch_angle_of_a_spiral

    In the geometry of spirals, the pitch angle [1] or pitch [2] of a spiral is the angle made by the spiral with a circle through one of its points, centered at the center of the spiral. Equivalently, it is the complementary angle to the angle made by the vector from the origin to a point on the spiral, with the tangent vector of the spiral at the ...

  4. Spiral - Wikipedia

    en.wikipedia.org/wiki/Spiral

    a three-dimensional curve that turns around an axis at a constant or continuously varying distance while moving parallel to the axis; a helix. The first definition describes a planar curve, that extends in both of the perpendicular directions within its plane; the groove on one side of a gramophone record closely approximates a plane spiral ...

  5. Logarithmic spiral - Wikipedia

    en.wikipedia.org/wiki/Logarithmic_spiral

    Logarithmic spiral (pitch 10°) A section of the Mandelbrot set following a logarithmic spiral. A logarithmic spiral, equiangular spiral, or growth spiral is a self-similar spiral curve that often appears in nature. The first to describe a logarithmic spiral was Albrecht Dürer (1525) who called it an "eternal line" ("ewige Linie").

  6. Alpha helix - Wikipedia

    en.wikipedia.org/wiki/Alpha_helix

    The pitch of the alpha-helix (the vertical distance between consecutive turns of the helix) is 5.4 Å (0.54 nm), which is the product of 1.5 and 3.6. The most important thing is that the N-H group of one amino acid forms a hydrogen bond with the C=O group of the amino acid four residues earlier; this repeated i + 4 → i hydrogen bonding is the ...

  7. Helix angle - Wikipedia

    en.wikipedia.org/wiki/Helix_angle

    The efficiency can be plotted versus the helix angle for a constant friction, as shown in the adjacent diagram. The maximum efficiency is a helix angle between 40 and 45 degrees, however a reasonable efficiency is achieved above 15°. Due to difficulties in forming the thread, helix angle greater than 30° are rarely used.

  8. Triple helix - Wikipedia

    en.wikipedia.org/wiki/Triple_helix

    The collagen triple helix is a triple helix formed from three separate protein helices, spiraling around the same axis. In the fields of geometry and biochemistry, a triple helix (pl.: triple helices) is a set of three congruent geometrical helices with the same axis, differing by a translation along the axis. This means that each of the ...

  9. Lead (engineering) - Wikipedia

    en.wikipedia.org/wiki/Lead_(engineering)

    In these screws, the lead is equal to the pitch multiplied by the number of "starts". Lead angle is the angle between the helix and a plane of rotation. It is the complement of the helix angle, and is used for convenience in worms and hobs. It is understood to be at the standard pitch diameter unless otherwise specified.