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  2. Helium-3 - Wikipedia

    en.wikipedia.org/wiki/Helium-3

    Since the atmosphere of the Earth has a mass of about 5.14 × 10 18 kilograms (1.133 × 10 19 lb), [24] the mass of 3 He in the Earth's atmosphere is the product of these numbers, or about 37,000 tonnes (36,000 long tons; 41,000 short tons) of 3 He. (In fact the effective figure is ten times smaller, since the above ppm are ppmv and not ppmw.

  3. Isotopes of helium - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_helium

    1 H + 1 H → 2 H + e + + ν e + 0.42 MeV. The hypothetical effect of a bound diproton on Big Bang and stellar nucleosynthesis , has been investigated. [ 18 ] Some models suggest that variations in the strong force allowing a bound diproton would enable the conversion of all primordial hydrogen to helium in the Big Bang, which would be ...

  4. Orders of magnitude (mass) - Wikipedia

    en.wikipedia.org/wiki/Orders_of_magnitude_(mass)

    Mass equivalent of the energy of a photon at the peak of the spectrum of the cosmic microwave background radiation (0.235 meV/c 2) [3] 10 −36: 1.8 × 10 −36 kg 1 eV/c 2, the mass equivalent of one electronvolt [4] 3.6 × 10 −36 kg Electron neutrino, upper limit on mass (2 eV/c 2) [5] 10 −33 quectogram (qg) 10 −31: 9.11 × 10 −31 kg

  5. Reduced mass - Wikipedia

    en.wikipedia.org/wiki/Reduced_mass

    Given two bodies, one with mass m 1 and the other with mass m 2, the equivalent one-body problem, with the position of one body with respect to the other as the unknown, is that of a single body of mass [1] [2] = = + = +, where the force on this mass is given by the force between the two bodies.

  6. Earth mass - Wikipedia

    en.wikipedia.org/wiki/Earth_mass

    An Earth mass (denoted as M 🜨, M ♁ or M E, where 🜨 and ♁ are the astronomical symbols for Earth), is a unit of mass equal to the mass of the planet Earth.The current best estimate for the mass of Earth is M 🜨 = 5.9722 × 10 24 kg, with a relative uncertainty of 10 −4. [2]

  7. Specific surface area - Wikipedia

    en.wikipedia.org/wiki/Specific_surface_area

    Specific surface area (SSA) is a property of solids defined as the total surface area (SA) of a material per unit mass, [1] (with units of m 2 /kg or m 2 /g). Alternatively, it may be defined as SA per solid or bulk volume [ 2 ] [ 3 ] (units of m 2 /m 3 or m −1 ).

  8. Atomic units - Wikipedia

    en.wikipedia.org/wiki/Atomic_units

    Mass = 1 a.u. of mass; Charge = −1 a.u. of charge; Orbital radius = 1 a.u. of length; Orbital velocity = 1 a.u. of velocity [44]: 597 Orbital period = 2π a.u. of time; Orbital angular velocity = 1 radian per a.u. of time; Orbital momentum = 1 a.u. of momentum; Ionization energy = ⁠ 1 / 2 ⁠ a.u. of energy

  9. SI base unit - Wikipedia

    en.wikipedia.org/wiki/SI_base_unit

    mass "The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10 −34 when expressed in the unit J s, which is equal to kg m 2 s −1, where the metre and the second are defined in terms of c and ∆ν Cs." [1] The mass of one litre of water at the ...