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Homework Help: Direction of vectors

  1. Sep 16, 2011 #1
    1. The problem statement, all variables and given/known data:
    Vector is directed along the positive y-axis and has magnitude 9.0 units. Vector is directed along the negative x-axis and has magnitude 5.0 unit.
    -> ->
    (a)What are the magnitude and direction of A + B? magnitude = squareroot of 9^2+5^2=10
    -> ->
    (b)How do I find direction of A + B _________° counterclockwise from the +x-axis

    -> ->
    (c) What are the x- and y-components of B − A ?
    x = ____________ unit(s)
    y = ____________ unit(s)

    What equations do I need to find parts B and C
  2. jcsd
  3. Sep 16, 2011 #2


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    Homework Helper

    Draw the situation and you will see a triangle that will enable you to find the direction relative to either the positive y-axis or the negative x-axis, depending which way you calculate it. The is the second part of part (a)

    You should then be able to relate that angle to the angle with the positive x-axis. part (b)

    Also your answer of 10 has either been rounded off a bit or your arithmetic is lacking.

    The usual requirement is to "follow your calculator" and have an answer with far too many decimal places, then round the answer off appropriately, just to show you recognise the real answer, and the precision you should be claiming.

    For Part (c) a simple sketch should help again.
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