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Value squared a dot product?

  1. Feb 19, 2013 #1
    I was recently going through the proof of Compton scattering and I saw that they took a square value and wrote it as p^2=p(dot)p= etc... Is this true or all squared values?
     
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  3. Feb 19, 2013 #2

    SteamKing

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    Use the definition of dot product and see what you get for a general vector.
     
  4. Feb 19, 2013 #3
    <A,A>=AAcos(0)=AA(1)=AA=A^2

    So this only applies when numbers are squared. I just find it strange that the dot product only applies to when normal multiplication is the square of a number and not at any other cases for example if A=/=B AB=/=ABcosθ. I guess I just don't understand where the dot product comes from enough to understand why it works like this.
     
  5. Feb 20, 2013 #4

    SteamKing

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    A dot B can be thought of a the projection of A onto B. If A and B are the same vector, then A dot B = A^2
     
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