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  2. Natural logarithm of 2 - Wikipedia

    en.wikipedia.org/wiki/Natural_logarithm_of_2

    In a third layer, the logarithms of rational numbers r = ⁠ a / b ⁠ are computed with ln(r) = ln(a) − ln(b), and logarithms of roots via ln n √ c = ⁠ 1 / n ⁠ ln(c).. The logarithm of 2 is useful in the sense that the powers of 2 are rather densely distributed; finding powers 2 i close to powers b j of other numbers b is comparatively easy, and series representations of ln(b) are ...

  3. tf–idf - Wikipedia

    en.wikipedia.org/wiki/Tf–idf

    Since the ratio inside the idf's log function is always greater than or equal to 1, the value of idf (and tf–idf) is greater than or equal to 0. As a term appears in more documents, the ratio inside the logarithm approaches 1, bringing the idf and tf–idf closer to 0.

  4. Specific strength - Wikipedia

    en.wikipedia.org/wiki/Specific_strength

    One Yuri equals 1 Pa⋅m 3 /kg or 1 N⋅m/kg, which is the breaking/yielding force per linear density of the cable under tension. [ 42 ] [ 43 ] A functional Earth space elevator would require a tether of 30–80 megaYuri (corresponding to 3100–8200 km of breaking length).

  5. Ultimate tensile strength - Wikipedia

    en.wikipedia.org/wiki/Ultimate_tensile_strength

    The ultimate tensile strength of a material is an intensive property; therefore its value does not depend on the size of the test specimen.However, depending on the material, it may be dependent on other factors, such as the preparation of the specimen, the presence or otherwise of surface defects, and the temperature of the test environment and material.

  6. Abundance of elements in Earth's crust - Wikipedia

    en.wikipedia.org/wiki/Abundance_of_elements_in...

    Abundance (atom fraction) of the chemical elements in Earth's upper continental crust as a function of atomic number; [5] siderophiles shown in yellow Graphs of abundance against atomic number can reveal patterns relating abundance to stellar nucleosynthesis and geochemistry.

  7. Age of the universe - Wikipedia

    en.wikipedia.org/wiki/Age_of_the_universe

    The value of the age correction factor, , is shown as a function of two cosmological parameters: the current fractional matter density and cosmological constant density . The best-fit values of these parameters are shown by the box in the upper left; the matter-dominated universe is shown by the star in the lower right.

  8. Hammett equation - Wikipedia

    en.wikipedia.org/wiki/Hammett_equation

    As the value of ρ is related to the charge during the rate determining step, mechanisms can be devised based on this information. If the mechanism for the reaction of an aromatic compound is thought to occur through one of two mechanisms, the compound can be modified with substituents with different σ values and kinetic measurements taken.

  9. Composition of the human body - Wikipedia

    en.wikipedia.org/wiki/Composition_of_the_human_body

    Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.