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Find V_0 in the circuit (6 elements)

  1. Sep 12, 2006 #1
    [​IMG]

    Use conservation of energy to solve for [itex]V_0[/itex].

    [tex]P_1\,=\,(30V)\,(-6A)\,=\,-180W[/tex]
    [tex]P_2\,=\,(12V)\,(6A)\,=\,72W[/tex]
    [tex]P_3\,=\,(V_0)\,(3A)\,=\,(3V_0)W[/tex]
    [tex]P_4\,=\,(28V)\,(2A)\,=\,56W[/tex]
    [tex]P_5\,=\,(28V)\,(1A)\,=\,28W[/tex]
    [tex]P_6\,=\,(10V)\,(-3A)\,=\,-30W[/tex]

    [tex]\sum\,p\,=\,p_1\,+\,p_2\,+\,p_3\,+\,p_4\,+\,p_5\,+\,p_6[/tex]

    [tex]\sum\,p\,=\,(-180W)\,+\,(72W)\,+\,[(3V_0)W]\,+\,(56W)\,+\,(28W)\,+\,(-30W)[/tex]

    [tex]3V_0\,=\,54W[/tex]

    [tex]V_0\,=\,18\,V[/tex]

    Does this look right?
     
    Last edited: Sep 12, 2006
  2. jcsd
  3. Sep 12, 2006 #2

    berkeman

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    Staff: Mentor

    Looks okay until the last step (units).

    EDIT -- BTW, this belongs in the homework forums, not the general forums.
     
  4. Sep 12, 2006 #3
    Do you mean the summation of the p's? I don't see a unit error, could you point it out please:)

    I didn't see the "Engineering" Forum over at Homework help section, but now I found it, thanks for the heads up!
     
  5. Sep 12, 2006 #4

    berkeman

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    Staff: Mentor

    Vo should not have units of watts. Just a small typo.
     
  6. Sep 12, 2006 #5
    OIC, thank you!

    [itex]V_0[/itex] should have units of Volts!

    Other than that, the problem looks OK?

    I will post other problems in the homework section, thanks for the help!
     
  7. Sep 21, 2006 #6
    it is right if you are taking (3v) as a combination volt*amp. as previously u have takev 3*vo as power. so it looks right to me.
     
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