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Homework Help: Vector questions

  1. Sep 6, 2008 #1
    1. The problem statement, all variables and given/known data

    so i have this question that says
    express the following in terms of their normal and tangential components. be sure to define the positive direction for both axes.
    so the first diagram has a board with a vector pointing upward toward the right. the angle formed by this (angle on the right) is 40 degrees. how do i go about doing this if i have no lengths for the sides or the vector. i know that the answer is going to be xn+yt something but i dont know how to find x (the normal) and y (the tangential.)
    the next diagram as the slanted board with a vector pointing upward to the right, but now it gives the angle on the outside of the triangle that can be formed, which means te inside angle would be 180-155. but i still dont know how to find lengths of the sides. or do i not have to.
  2. jcsd
  3. Sep 6, 2008 #2


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    Homework Helper

    Can you explain what you mean by "board"? Just a physical object like a board with a vector acting though the middle?

    One way of expressing vectors is to use trig functions with the x and y components. + V Sine(40) and + V Cos(40) as they would both be positive. Is it possible they want you to express the vector of the second diagram with similar components but with a sign appropriate to positive x and y and appropriate angle?

    Without further information though it is difficult to understand where you are stuck.
  4. Sep 6, 2008 #3
    yeah the board is just the line that the vector is coming off of. like if you look at the letter "y" thats what my diagram looks like. the straight line in the y would be the board and the small line that forms the y is the vector. and the angle in the y is 40 degrees. so you think i could just have the answer be cos40(x) t + sin40(y) n, where x is the adjacent side and y is the opposite side. and then just express it in that way? because i myself dont see any way that i could actually solve for it.
  5. Sep 6, 2008 #4


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    There is little else from what I am given. Just remember to adjust the signs of the x component if positive x is to the right and the vector is pointing to the left. (Likewise for positive and negative normal directions.)

    All I can say is good luck.
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