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  2. Minute and second of arc - Wikipedia

    en.wikipedia.org/wiki/Minute_and_second_of_arc

    A second of arc, arcsecond (abbreviated as arcsec), or arc second, denoted by the symbol ″, [2] is a unit of angular measurement equal to ⁠ 1 / 60 ⁠ of a minute of arc, ⁠ 1 / 3600 ⁠ of a degree, [1] ⁠ 1 / 1 296 000 ⁠ of a turn, and ⁠ π / 648 000 ⁠ (about ⁠ 1 / 206 264.8 ⁠) of a radian.

  3. Stokes number - Wikipedia

    en.wikipedia.org/wiki/Stokes_number

    [2] In experimental fluid dynamics, the Stokes number is a measure of flow tracer fidelity in particle image velocimetry (PIV) experiments where very small particles are entrained in turbulent flows and optically observed to determine the speed and direction of fluid movement (also known as the velocity field of the fluid). For acceptable ...

  4. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    The correct branch of the multiple valued function arctan x to use is the one that makes ν a continuous function of E(M) starting from ν E=0 = 0. Thus for 0 ≤ E < π use arctan x = arctan x, and for π < E ≤ 2π use arctan x = arctan x + π. At the specific value E = π for which the argument of tan is infinite, use ν = E.

  5. Milliradian - Wikipedia

    en.wikipedia.org/wiki/Milliradian

    A milliradian (SI-symbol mrad, sometimes also abbreviated mil) is an SI derived unit for angular measurement which is defined as a thousandth of a radian (0.001 radian). ). Milliradians are used in adjustment of firearm sights by adjusting the angle of the sight compared to the barrel (up, down, left, or

  6. Quartz crystal microbalance - Wikipedia

    en.wikipedia.org/wiki/Quartz_crystal_microbalance

    Here Z F is the acoustic impedance of the film (Z F = ρ F c F = (ρ F G f) 1/2)= (ρ F /J f) 1/2), k F is the wave vector and d F is the film thickness. J f is the film's viscoelastic compliance, ρ F is the density. The poles of the tangent (k F d F = π/2) define the film resonances. [55] [56] At the film resonance, one has d F = λ/4. The ...

  7. Projectile motion - Wikipedia

    en.wikipedia.org/wiki/Projectile_motion

    Solving (1) is an elementary differential equation, thus the steps leading to a unique solution for v x and, subsequently, x will not be enumerated. Given the initial conditions v x = v x 0 {\displaystyle v_{x}=v_{x0}} (where v x0 is understood to be the x component of the initial velocity) and x = 0 {\displaystyle x=0} for t = 0 {\displaystyle ...

  8. Kurtosis - Wikipedia

    en.wikipedia.org/wiki/Kurtosis

    Setting a 2 = 2m − 3 makes the variance equal to unity. Then the only free parameter is m , which controls the fourth moment (and cumulant) and hence the kurtosis. One can reparameterize with m = 5 / 2 + 3 / γ 2 {\textstyle m=5/2+3/\gamma _{2}} , where γ 2 {\displaystyle \gamma _{2}} is the excess kurtosis as defined above.

  9. Assured clear distance ahead - Wikipedia

    en.wikipedia.org/wiki/Assured_Clear_Distance_Ahead

    Substituting the small angle approximations, and exploiting that the product of a small angle squared, in radians, with the friction coefficient, θ 2 μ, is insignificant (for a steep 20% slope and a good friction coef. of 0.8, this equals (.2) 2 x0.8≈0.03):