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Homework Help: Simple question: unit vector

  1. Jan 22, 2005 #1

    I'm wondering if anyone knows how to input a unit vector that lies between X and Y axes, into a Master Physics answering box.

    One of the questions I'm working on required a unit vector (to point a direction) to be part of the answer. I know that the direction is between the X and Y axes so I tried using (sqrt0.5,sqrt0.5,0) as my unit vector but that didn't work out. It seems that they want the the unit vector in terms of x_unit, y_unit, z_unit (in mastering physics x_unit = x capped/x with a hat).

    Any helps would be greatly appreciated.
  2. jcsd
  3. Jan 22, 2005 #2
    Should I try using x_unit*y_unit as my unit vector?

    I know that x_unit, y_unit, z_unit represent unit vectors in x, y, z directions, respectively. I have only 2 more chances left.

    Should I try this -k*(q_0)*(q_3)*y_unit*x_unit/(sqrt((d_2)^2+(d_2)^2))^2

    (It's a force in an xy-plane.)
    Last edited: Jan 22, 2005
  4. Jan 22, 2005 #3
    gah i hate mastering physics, i had to use it for Mechanics last semester :/

    Usually its expressing the vector using it's components such as
    Last edited: Jan 22, 2005
  5. Jan 22, 2005 #4
    After searching on the internet, I found that i_unit*j_unit = 0 so the answer in my previous reply is probably wrong. Anyone?
  6. Jan 22, 2005 #5
    So would the unit vector in an xy-planet = ((x_unit)^2+(y_unit)^2))^1/2? = (sqrt0.5, sqrt0.5, 0)?

    But wouldn't that "w=((x_unit)^2+(y_unit)^2+(z_unit)^2)^1/2" be a scalar quantity? then isn't it no longer a vector and cannot act as a (unit) direction vector?

    Thanks in advance
  7. Jan 23, 2005 #6
    OK, how about if I ask this. I want to write a unit vector that lies 45 deg. from either x/y axis, interm of unit vectors x_unit and y_unit, is it possible to do that?
  8. Jan 23, 2005 #7
    I figured it out, thanks for your help.
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