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Homework Help: Calculating the Unit Vectors

  1. Feb 13, 2010 #1
    1. The problem statement, all variables and given/known data
    http://img22.imageshack.us/img22/1254/10031833.jpg [Broken]

    2. Relevant equations

    3. The attempt at a solution
    My attempt was based on the idea that both triangles formed by the vector components (x component, y component, and the hypotenuse which is the magnitude of the vector itself) would be similar.

    I took the length of each of the sides, -3.20 for x and 2.10 for y and individually solved for the unit vector by setting up this relationship:
    (length of component)/(length of hypotenuse)=(length unit component)/1

    The system rejected both of my answers. For x i got -0.836 and for y i got 0.549.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Feb 13, 2010 #2
    Your answer looks fine to me. I calculated the same value for the two components. I like that similar triangle method to find unit vectors. In vector classes, you usually just think about it this way(which involves the exact same math): you have a vector A with magnitude A at angle C. You want the same direction(the same angle C) at a magnitude of 1, so you divide by A(the hypotenuse). So yeah, it's the same calculation: each component divided by the hypotenuse.
    Last edited by a moderator: May 4, 2017
  4. Feb 13, 2010 #3
    Maybe it has to do something with unit vector notation. is there a specific notation?Or maybe we both got the answer wrong. Either way im not getting my homework credit right now
  5. Feb 13, 2010 #4
    please help me figure this out, or at least give me your opinions.
  6. Feb 13, 2010 #5
    What are you calculating here? Are not the components given in the problem?
    The x component is -3.20 and the y component is +2.10, according to the problem. Am I missing something here?
  7. Feb 16, 2010 #6
    it turns out that there isn't any calculation necessary, and your answer is correct. i thought the question was asking for a unit vector with the same angle as the given vector.
    A Unit vector is a vector with a magnitude of 1, thats where all of my calculations came from - which apparently were unnecessary.
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