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Molecule Kinetics

  1. Apr 6, 2007 #1
    1. The problem statement, all variables and given/known data

    A space vehicle returning from the Moon enters Earth’s atmosphere at a speed of about 4.9E4 km/h. Molecules (assum nitrogen) striking the nose of the vehicle with this speed correspond to what temperature?

    2. Relevant equations

    KE=0.5mv^2=kT
    k: constant

    3. The attempt at a solution

    I'm lost.
     
  2. jcsd
  3. Apr 6, 2007 #2

    Dick

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    Look up the mass of an N2 molecule and Boltzmann's constant, k, put them into your first equation and solve for T. ????
     
  4. Apr 6, 2007 #3
    Can't look up mass, only molecular weight. Where mass=#mols*molecular weight.
     
  5. Apr 6, 2007 #4

    Dick

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    You can so look up the mass of a single nitrogen atom. It's in the periodic table in atomic mass units. What's an atomic mass unit in kilograms? Can also be looked up.
     
  6. Apr 6, 2007 #5
    N=14.00674u
    1 u ≈ 1.66053886 × 10−27 kg

    Then just solve for T with 0.5mv^2=kT?

    Thanks,
    Brandon
     
  7. Apr 6, 2007 #6

    Dick

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    Except remember the question says 'molecules' and nitrogen is N2 (two nitrogen atoms).
     
    Last edited: Apr 6, 2007
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