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Homework Help: Find the Vector problem

  1. Mar 2, 2009 #1
    1. The problem statement, all variables and given/known data

    Suppose n is normal to a plane and v is parallel to the plane. Describe how you would find a vector u that is both perpendicular to v and parallel to the plane.



    2. Relevant equations

    Cross product, dot product

    3. The attempt at a solution

    Since u is perpendicular to v, u dot v = 0. U is also parallel to the plane so u will be perpendicular to n, so u dot n=0.

    How would I do the rest of it ?
     
  2. jcsd
  3. Mar 2, 2009 #2
    Well, I can't give you the solution, but I will tell you that if I gave you a hint, you'd probably know it. Let's try.

    You've used the dot product. Does the cross product help?
     
  4. Mar 2, 2009 #3

    Dick

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    You didn't use the cross product. axb is perpendicular to both a and b, right?
     
  5. Mar 2, 2009 #4
    Oh so u is basically n cross v ?
     
  6. Mar 2, 2009 #5

    Dick

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    Sure. Or any multiple thereof.
     
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