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  2. Shear velocity - Wikipedia

    en.wikipedia.org/wiki/Shear_velocity

    It [clarification needed] can be approximated as 2 / 3 to 3 / 4 of the average height of the obstacles. [3] For example, if estimating winds over a forest canopy of height 30 m, the zero-plane displacement could be estimated as d = 20 m. Thus, you can extract the friction velocity by knowing the wind velocity at two levels (z).

  3. List of NP-complete problems - Wikipedia

    en.wikipedia.org/wiki/List_of_NP-complete_problems

    The variant where variables are required to be 0 or 1, called zero-one linear programming, and several other variants are also NP-complete [2] [3]: MP1 Some problems related to Job-shop scheduling; Knapsack problem, quadratic knapsack problem, and several variants [2] [3]: MP9 Some problems related to Multiprocessor scheduling

  4. Inclined plane - Wikipedia

    en.wikipedia.org/wiki/Inclined_plane

    The problem of calculating the force required to push a weight up an inclined plane (its mechanical advantage) was attempted by Greek philosophers Heron of Alexandria (c. 10 - 60 CE) and Pappus of Alexandria (c. 290 - 350 CE), but their solutions were incorrect. [23] [24] [25]

  5. Capstan equation - Wikipedia

    en.wikipedia.org/wiki/Capstan_equation

    For instance, the factor "153,552,935" (5 turns around a capstan with a coefficient of friction of 0.6) means, in theory, that a newborn baby would be capable of holding (not moving) the weight of two USS Nimitz supercarriers (97,000 tons each, but for the baby it would be only a little more than 1 kg). The large number of turns around the ...

  6. Crossed ladders problem - Wikipedia

    en.wikipedia.org/wiki/Crossed_ladders_problem

    The value D is found in the solution as the real part of the difference in the squares of the complex coordinates of the two walls. The imaginary part = 2X a Y a = 2X b Y b (walls a and b). The short ladder in the complex solution in the 3, 2, 1 case appears to be tilted at 45 degrees, but actually slightly less with a tangent of 0.993.

  7. Darcy friction factor formulae - Wikipedia

    en.wikipedia.org/wiki/Darcy_friction_factor_formulae

    Serghides's solution is used to solve directly for the Darcy–Weisbach friction factor f for a full-flowing circular pipe. It is an approximation of the implicit Colebrook–White equation. It was derived using Steffensen's method. [12] The solution involves calculating three intermediate values and then substituting those values into a final ...

  8. Stokes' law - Wikipedia

    en.wikipedia.org/wiki/Stokes'_law

    g is the gravitational acceleration [m/s 2] Requiring the force balance F d = F e and solving for the velocity v gives the terminal velocity v s. Note that since the excess force increases as R 3 and Stokes' drag increases as R, the terminal velocity increases as R 2 and thus varies greatly with particle

  9. Ladder - Wikipedia

    en.wikipedia.org/wiki/Ladder

    An extension ladder. A ladder is a vertical or inclined set of rungs or steps commonly used for climbing or descending. There are two types: rigid ladders that are self-supporting or that may be leaned against a vertical surface such as a wall, and rollable ladders, such as those made of rope or aluminium, that may be hung from the top.