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Insulation=> simple problem just confused a bit.

  1. Mar 25, 2008 #1

    ~christina~

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    Gold Member

    1. The problem statement, all variables and given/known data
    A house has well insulated walls. It contains a vol of 100m^3 of air at 300K

    a) calculate the E required to increase the T of the diatomic gas by 1.00C

    b) If this E could be used to lift an object of mass m through a height of 2.00m what is the mass of m?


    2. Relevant equations
    [tex]Q=m C_v \Delta T[/tex]= > constant V
    [tex]\Delta U= Q [/tex]
    [tex]C_v= 5R/2 [/tex]

    [tex]Q=mC_p \Delta T [/tex]=> constant P
    [tex]\Delta U= Q + W= nC_p \Delta T + (-P\Delta V) [/tex]
    [tex]C_p= 7R/2[/tex]

    3. The attempt at a solution

    a)calculate the E required to increase the T of the diatomic gas by 1.00C

    I would think that the insulation would make the volume be constant but that's what I'm not sure about. (I was thinking that the temperature would be constant but if they ask how much E is needed to raise the temperature then it can't be that the temperature would be the same...)

    b) b) If this E could be used to lift an object of mass m through a height of 2.00m what is the mass of m?
    would I just use [tex] \Delta PE= mgh [/tex]and find m ?

    Help please..

    Thank you very much.
     
    Last edited: Mar 25, 2008
  2. jcsd
  3. Mar 26, 2008 #2

    ~christina~

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    can someone help me please?

    I have a quiz and if no one does then I'll be forced to assume that the volume doesn't change even if it may be incorrect. :frown:
     
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