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  2. Spherical shell - Wikipedia

    en.wikipedia.org/wiki/Spherical_shell

    An approximation for the volume of a thin spherical shell is the surface area of the inner sphere multiplied by the thickness t of the shell: [2] V ≈ 4 π r 2 t , {\displaystyle V\approx 4\pi r^{2}t,}

  3. Tree girth measurement - Wikipedia

    en.wikipedia.org/wiki/Tree_girth_measurement

    An Excel spreadsheet can be used to determine the rate the apparent size of the scale changes with distance, and that value can be used to calculate the diameter of the tree given that the tree is circular in cross section and the distance to the front side of the tree is known. Girth then is calculated by multiplying the diameter by pi.

  4. Gurney equations - Wikipedia

    en.wikipedia.org/wiki/Gurney_equations

    Uniformly initiated spherical charge imploding an inner mass - spherical shell explosive charge of mass C, outer tamper layer of mass N, and inner imploding spherical flyer shell of mass M A special case is a hollow sphere of explosives, initiated evenly around its surface, with an outer tamper and inner hollow shell which is then accelerated ...

  5. Shell theorem - Wikipedia

    en.wikipedia.org/wiki/Shell_theorem

    The remaining mass is proportional to (because it is based on volume). The gravitational force exerted on a body at radius r will be proportional to m / r 2 {\displaystyle m/r^{2}} (the inverse square law ), so the overall gravitational effect is proportional to r 3 / r 2 = r {\displaystyle r^{3}/r^{2}=r} , so is linear in r {\displaystyle r} .

  6. Spherical cap - Wikipedia

    en.wikipedia.org/wiki/Spherical_cap

    An example of a spherical cap in blue (and another in red) In geometry, a spherical cap or spherical dome is a portion of a sphere or of a ball cut off by a plane.It is also a spherical segment of one base, i.e., bounded by a single plane.

  7. Particle-size distribution - Wikipedia

    en.wikipedia.org/wiki/Particle-size_distribution

    D 50: Mass-median-diameter (MMD). The log-normal distribution mass median diameter. The MMD is considered to be the average particle diameter by mass. σ g: Geometric standard deviation. This value is determined mathematically by the equation: σ g = D 84.13 /D 50 = D 50 /D 15.87. The value of σ g determines the slope of the least-squares ...

  8. Strouhal number - Wikipedia

    en.wikipedia.org/wiki/Strouhal_number

    Given = where m is mass, V is volume, and is density, we can see mass is directly related to size as volume scales with length (L). Taking the volume to be L 3 {\displaystyle L^{3}} , we can directly relate mass and size as

  9. Characteristic length - Wikipedia

    en.wikipedia.org/wiki/Characteristic_length

    In physics, a characteristic length is an important dimension that defines the scale of a physical system. Often, such a length is used as an input to a formula in order to predict some characteristics of the system, and it is usually required by the construction of a dimensionless quantity, in the general framework of dimensional analysis and in particular applications such as fluid mechanics.