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First law - why is there no change in KE for this Q? watch

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    A liquid stream is heated from 25 to 80 C. The inlet and outlet pipes have the same diameter, and there is no change in elevation. Identify (0, -ve, or +ve) U, Q and W and the other terms.

    So U = 0 due to steady state
    W = 0
    Q = +ve
    PE = 0 since no change in elevation

    For KE I said it would be +ve because the heat would increase the speed of molecules right? But it says it is 0 as well. Why?
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    The first law of thermal dynamics doesn't detail with PE. The first law only states energy can not be destroyed or created. At least that it was I believe you are asking.
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    This is first law for open systems
 
 
 
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Updated: May 22, 2010

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