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Homework Help: How this unit comes like that ?

  1. Nov 3, 2012 #1
    How this unit comes

    R = specific volume X (pressure / Temperature )

    0.9m^3/kg (1.3X10^5 N/m^2 / 408 K )

    R = 286 KJ/KgK

    please can any one explain to me how the unit ( KJ/KgK ) comes ??
     
  2. jcsd
  3. Nov 3, 2012 #2

    Borek

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    Staff: Mentor

    kJ/(kg*K) - looks quite straightforward, where is the problem?
     
  4. Nov 3, 2012 #3
    Hi sir .. I know the unit is correct but when I try to solve by my self I don't get that uint

    please help ..
     
  5. Nov 3, 2012 #4
    r = volume * pressure / temperature
    = (length*length*length)/mass * Newtons/(length*length) / temperature
    = length*Newtons/(temperature * mass)

    = Joules/(temperature * mass)
     
  6. Nov 3, 2012 #5

    Borek

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    Staff: Mentor

    Show what you did then and we will try to find out where did you get wrong.
     
  7. Nov 3, 2012 #6
    1 Joule = 1 N-m
     
  8. Nov 4, 2012 #7

    Borek

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    Staff: Mentor

    Dash that looks like a minus is not the luckiest selection of the symbol in this context.

    1 Joule = 1 Newton * m

    is much less ambiguous.
     
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