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Homework Help: Vector trouble

  1. Nov 3, 2005 #1

    DB

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    when a question gives u vectors in polar form, calling them A,B,C,D then askes you to simply for example: A - 4C + D, what am i supposed to do? is it just vector sum and difference? how do i multiply a vector by 4?

    thanks
     
  2. jcsd
  3. Nov 3, 2005 #2
    4(xi+yj+zk)=4xi+4yj+4zk
     
  4. Nov 3, 2005 #3

    DB

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    sry i didnt mention we were working in 2D, but wat are i and j?
     
  5. Nov 3, 2005 #4
    i and j is the subscript used to designate the x and y axis
     
  6. Nov 3, 2005 #5

    DB

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    o i see, sry to be a pain in the butt, but then wat are x and y?
     
  7. Nov 3, 2005 #6
    the coefficients of i and j
     
  8. Nov 3, 2005 #7

    Integral

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    As used above, i and j, represent unit vectors, i in the x direction, j in the y. In 3d you also have k, the unit vector in the z direction.

    I would assume that you are taking some form of a math class, have you read your text?
     
  9. Nov 3, 2005 #8

    DB

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    so 4 * Vector 25, 340 degrees would be 4(23.5+8.6) aproxx??
     
  10. Nov 3, 2005 #9

    DB

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    physics, my teacher hasnt given us any reading, he just said see if u can get these problems
     
  11. Nov 3, 2005 #10

    DB

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    is 4(23.5+8.6) right? wat i did was set up the the vector on a cartesian plane and use trig to solve the lenghts, would it be 4(23.5+ -8.6) because the triangle is in the 4th quadrant, or would i take the absolute value?
     
  12. Nov 4, 2005 #11
    If you are trying to work out 4V as a vector, and V is something at 340 degrees, and at a magnitude of 25, then the vector can be written as
    [tex]v = 4(23.5i-8.6j) [/tex]
    (approx). The i and j are there to show they are the different components of v.
    By the way, I hate this latex thing, I was trying to get the i and j go bold in tex mode, but failed, oh well.
     
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