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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. Dilution refrigerator - Wikipedia

    en.wikipedia.org/wiki/Dilution_refrigerator

    That means that, to reduce the temperature by a factor 2, one needs to increase the diameter by a factor of 8 and the length by a factor of 256. Hence the volume should be increased by a factor of 2 14 = 16,384. In other words: every cm 3 at 2 mK would become 16,384 cm 3 at 1 mK. The machines would become very big and very expensive.

  8. 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).

  9. Atomic units - Wikipedia

    en.wikipedia.org/wiki/Atomic_units

    Hartree defined units based on three physical constants: [1]: 91 Both in order to eliminate various universal constants from the equations and also to avoid high powers of 10 in numerical work, it is convenient to express quantities in terms of units, which may be called 'atomic units', defined as follows: