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Homework Help: Thermal Physics Question

  1. Nov 18, 2007 #1
    1. The problem statement, all variables and given/known data

    An oxygen supply system mixes oxygen at 105 K and room air at 307 K at equal mass flow rates. What is the temperature of the resulting mixture in K? (c of oxygen = 918 J/kgK, c of air = 1012 J/kgK)

    2. Relevant equations

    [tex]Q=mc\Delta T[/tex] and [tex]Q=mL_f[/tex]
    3. The attempt at a solution

    (105 x 918 + 1012 x 307) / (918 + 1012) = 210 K ( not a single inkling about the validity of the answer ) -_- . The inadequancy of my lecture notes really leaves me clueless =/
    Last edited: Nov 18, 2007
  2. jcsd
  3. Nov 18, 2007 #2
    firstly, we must define delta T clearly. delta T is the change in temperature of both mixtures, and we can define delta T as the temepreature change from 105K, and then the temperature change for the room air is (307-105)=202K, 202-deltaTK.

    Equate both equations together in the first equation you gave and you have the answer.
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