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Homework Help: Unit Vectors

  1. Feb 5, 2009 #1
    1. The problem statement, all variables and given/known data
    A golf ball is hit off a tee at the edge of a cliff. Its x and y coordinates as functions of time are given by the following expressions.
    x = (16.0 m/s)t
    y = (3.30 m/s)t - (4.90 m/s2)t^2

    Write a vector expression for the ball's position as a function of time, using the unit vectors i and j. (Use t, i and j as necessary.)

    2. Relevant equations

    3. The attempt at a solution
    The best i am coming up with is
    (19.30 m/s)t i - (4.90 m/s^2)t^2 j

    I know im missing something about the conversion but i dont know what, and am really confused about vectors

    EDIT: I realized what i did. I get really confused with the vectors. i didnt realize the two x was going to compose the i component and the y was going to compose the j component. Thank for the help, but TBH im glad a figured it out on my own...im sure ill remmeber now! Thanks
    THe answer i got was
    (16.0t) i + [(3.30t)-(4.9t^2)] j
    Last edited: Feb 5, 2009
  2. jcsd
  3. Feb 5, 2009 #2


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    Science Advisor

    Why did you just drop the (3.30 m/s)t part from the j component?

    Writing a position vector with i,j (and sometimes) k is just writing everything in the same equation, basically, with an i after the x component, a j after the y, and a k after the z. This is what it boils down to, there's a bit more to it than that and if you have any specific questions I could try to help with that.
  4. Feb 5, 2009 #3
    I didnt just drop the 3.3 i added it to the 16.0; i realized where i was mistaken at. check out the edit i just posted after you answered! Thank you for your help though! :-)
    Last edited: Feb 5, 2009
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