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  2. Grade (slope) - Wikipedia

    en.wikipedia.org/wiki/Grade_(slope)

    This means that for every 4 units (feet or metres) of horizontal distance there is a 1 unit (foot or metre) vertical change either up or down." [3] Any of these may be used. Grade is usually expressed as a percentage - converted to the angle α by taking the inverse tangent of the standard mathematical slope, which is rise / run or the grade ...

  3. Degree of curvature - Wikipedia

    en.wikipedia.org/wiki/Degree_of_curvature

    Other lengths may be used—such as 100 metres (330 ft) where SI is favoured or a shorter length for sharper curves. Where degree of curvature is based on 100 units of arc length, the conversion between degree of curvature and radius is Dr = 18000/π ≈ 5729.57795 , where D is degree and r is radius.

  4. Hazen–Williams equation - Wikipedia

    en.wikipedia.org/wiki/Hazen–Williams_equation

    V is velocity (in ft/s for US customary units, in m/s for SI units) k is a conversion factor for the unit system (k = 1.318 for US customary units, k = 0.849 for SI units) C is a roughness coefficient; R is the hydraulic radius (in ft for US customary units, in m for SI units) S is the slope of the energy line (head loss per length of pipe or h ...

  5. Stream gradient - Wikipedia

    en.wikipedia.org/wiki/Stream_gradient

    Stream gradient (or stream slope) is the grade (or slope) of a stream.It is measured by the ratio of drop in elevation and horizontal distance. [1] It is a dimensionless quantity, usually expressed in units of meters per kilometer (m/km) or feet per mile (ft/mi); it may also be expressed in percent (%).

  6. Track geometry - Wikipedia

    en.wikipedia.org/wiki/Track_geometry

    This is done by having a chord of 100 feet (30.48 m) connecting to two points on an arc of the reference rail, then drawing radii from the center to each of the chord's end points. The angle between the radii lines is the degree of curvature. [ 10 ]

  7. Area chart - Wikipedia

    en.wikipedia.org/wiki/Area_chart

    William Playfair is usually credited with inventing the area charts as well as the line, bar, and pie charts.His book The Commercial and Political Atlas, published in 1786, contained a number of time-series graphs, including Interest of the National Debt from the Revolution and Chart of all the Imports and Exports to and from England from the Year 1700 to 1782 that are often described as the ...

  8. Roof pitch - Wikipedia

    en.wikipedia.org/wiki/Roof_pitch

    Roof pitch is the steepness of a roof expressed as a ratio of inch(es) rise per horizontal foot (or their metric equivalent), or as the angle in degrees its surface deviates from the horizontal. A flat roof has a pitch of zero in either instance; all other roofs are pitched .

  9. Stocking (forestry) - Wikipedia

    en.wikipedia.org/wiki/Stocking_(forestry)

    When stocking, a tree's basal area is measured. The basal area is a cross-sectional area of the stump taken about 4.5 feet (1.4 m) above the ground. [7] The equation for calculating the basal area of trees in a stand is Basal Area = 0.005454 DBH 2, where DBH is the diameter of the tree at the aforementioned measuring height. [7]