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Homework Help: Physics homework questions

  1. Aug 31, 2009 #1
    Hey. Here are the questions I'm a bit stuck on:

    1) The joule is not a base unit. There are several equations which could be used to define the physical quantity energy. Find at least two of them

    2) Use one of the eqautions you have foundnto find the combination of base units equivalent to the joule.

    I have searched the internet but cannot find any relevant answers?

    I think it is along these lines, but im not sure:

    The joule is equal to:
    Newtons * metres
    Coulombs * volts
    Watts * seconds

    The joule is also equivalent to:
    metres^2 * kilograms * seconds^-2

    Any help and clarification would be much appreciated - thank you.
  2. jcsd
  3. Aug 31, 2009 #2


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    You need to write equations down that express some kind of energy. For example, what equation has something that is measured in Joules on the left side and Newtons*metres on the other. Do the same for the other two products of nits that you have listed.
  4. Sep 1, 2009 #3
    Hi. Thanks for your reply! What does the second question mean though? I'm struggling to understand. Thanks again.
  5. Sep 1, 2009 #4
    That is more or less the answer to your second part :)
    It is actually asking you to use dimensional/units analysis to determine the SI unit representation of the Joule. For instance with the equation W = Fd, by comparing the units on both sides of the equation, you can arrive at the SI units equivalent of the joule
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