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Homework Help: What then is in unit-vector notation

  1. Mar 29, 2007 #1
    1. The problem statement, all variables and given/known data

    In the product F = qv x B , take q = 4,
    v = 2.0i + 4.0j + 6.0k and F= 136i -176j + 72k.
    What then is in unit-vector notation if Bx = By?

    2. Relevant equations

    136i-176j+72k = 8i+16j+24k X Bxi+Byj+Bzk

    3. The attempt at a solution

    I am stuck with the above equation. How do I solve for Bxi, Byj and Bzk?

    136i-176j+72k=8i+16j+24k X Bxi+Byj+Bzk
    So If I find the determinant from the right hand side it's:
    136i-176j+72k=((16)(Bz)-(By)(24))i+((24)(Bx)-(Bz)(8))j+((8)(By)-(16)(Bx))k
    136i-176j+72k=(16Bz-24By)i+(24Bx-8Bz)j+(8By-16Bx)k

    Now what do I do???
     
  2. jcsd
  3. Mar 29, 2007 #2
    If i were you i'd post this on one of the math forums. This isn't likely to get much response here.
     
  4. Mar 29, 2007 #3

    Andrew Mason

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    Science Advisor
    Homework Helper

    Since i, j and k are mutually orthogonal unit vectors, then 16Bzi-24Bxi = 136i. You also know that Bx = By, so 8By-16Bx = 72 gives you the value for Bx and By. From that you can figure out Bz.

    AM
     
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