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Converting (having major trouble)

  1. Feb 7, 2007 #1
    I have a link to the image i am having trouble with it is D where i have to convert one SI unit, but really confuse how to do it.

    http://img267.imageshack.us/img267/9623/webassignvy9.jpg

    any help or explaination on how do the conversion would be very helpful.
     
  2. jcsd
  3. Feb 7, 2007 #2

    cepheid

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    Okay, I'll get you started. From your responses to the quiz, it is clear that you realize that:

    1 W = 1 J/s

    Therefore, 1 J = 1 W*s

    A joule of energy is the amount of energy expended after one second by something that uses one watt of power.

    Therefore

    1 kWh = ??? W*s

    well, how many watts in a kilowatt? How many seconds in an hour? It's really as simple as that!
     
  4. Feb 7, 2007 #3
    1 kWh = (10^3 W)(3600 sec.) = 3600000 W*s

    BTW, its not a quiz it's homework given to us to review for the quiz/test.
     
    Last edited: Feb 7, 2007
  5. Feb 7, 2007 #4

    cepheid

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    Ok, hw. Cool...

    So your answer looks right to me. In which case, if I'm reading your hw right, the cost is 7 cents per 3 600 000 joules = whatever

    Let me know if that gives you the right answer!
     
  6. Feb 7, 2007 #5
    7 cent is incorrect which i have tried earlier.
     
  7. Feb 8, 2007 #6

    cepheid

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    No no no! It's 7 cents for every kWh = 3600000 J. They want to know what it is on a PER JOULE basis. Now that you have the number of joules in a kWh, you can easily calculate the unit price PER JOULE.

    You were supposed to calculate the "whatever". That is your answer.
     
    Last edited: Feb 8, 2007
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