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Homework Help: Displacement of vectors

  1. Sep 5, 2011 #1
    Three displacement vectors of a croquet ball are shown in the figure, where || = 10.0 units, || = 35.0 units, and || = 10.0 units.
    p1-053.gif

    (a) Find the resultant in unit-vector notation.


    (b) Find the magnitude and direction of the resultant displacement.


    For part a, I broke each down vector into its compnents:

    Va: <0,10>

    Vb: x = r Cos o y = r Sin o
    x = (35) cos 45 y = (35) sin 45
    Vb = <24.75, 24.75>

    Vc: x = 10 Cos 45 y = 10 Sin 45
    = <-7.07,-7.07>


    Using the head to tail method, I simply added all the Vectors and got the Resultant vector as:
    17,7i + 27.7j

    For part b I used pythagorean's to find the magnitude which came out to:
    (17.7^2 + 27.7^2)^1/2 = 32.8

    Then I used inverse of Tan (27.7/17.7) which came to:
    57.4 degrees


    I'm almost certain this is correct but webassign keeps saying its wrong! Any help or input is greatly appreciated, thanks.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Sep 5, 2011 #2
    For the components of vector C you have two minus signs, there should only be one.
     
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