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Homework Help: A very simple question concerning the algebra of physics

  1. May 20, 2012 #1
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution

    Suppose I had an expression, for the sake of this post

    [tex]\frac{Ec^2}{mv}[/tex]

    we know that [tex]c^2 = \frac{E}{m}[/tex] so can the above expression be substituted as

    [tex]c^2 \frac{c^2}{v}[/tex]

    Yes, yes, I know this result is very uninteresting, I was just making a quick example. Thank you!
     
  2. jcsd
  3. May 20, 2012 #2
    I ask this because some work I am following states that if two particles are really close separated at a distance R then the momentum is large proportional to

    [tex]\frac{\hbar}{R}[/tex]

    Then it says that using a substitution then in E=pc

    [tex]E= \frac{\hbar c}{R}[/tex]

    so in this sense, if you can do it that way, you can also do it my way, the reversed way in the OP, right?
     
  4. May 20, 2012 #3

    Dick

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    Homework Helper

    So far so good. Is that the whole question? You can always substitute equal for equals.
     
  5. May 20, 2012 #4
    Thank you, that is all I wanted to know! :)
     
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