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Homework Help: Finding the magnitude of the resultant vectors

  1. Jun 21, 2012 #1
    I need help on how to solve this

    1. The problem statement, all variables and given/known data

    Three vectors, expressed in Cartesian coordinates are :
    S -> x( -3.5), y(+4.5)
    T -> x(0), y(-6.5)
    U -> x(+5.5), y(-2.5)

    what is the magnitude of the resultant vector S + T + U?

    The answer, according to my answer sheet is 4.9, but I dont know how to get that answer.

    Any help is greatly appreciated
  2. jcsd
  3. Jun 21, 2012 #2
    What is the magnitude of a vector?
  4. Jun 21, 2012 #3


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    Homework Helper

    Firstly, how would you go about adding one vector to another?
  5. Jun 24, 2013 #4

    There might be different ways to do it but here's how I did it.

    First, add up all of the x values: (-3.5) + 0 + 5.5 = 2
    then, add up all of the y values: 4.5 - 6.5 - 2.5 = -4.5

    Then, use the pythagorean theorem on the absolute value of x and y (disregard the negative signs).

    c^2 = a^2 + b^2
    c = sqrt(a^2 + b^2)
    = sqrt(2^2 + 4.5^2)
    = sqrt(4 + 20.25)
    = sqrt(24.25)
    = 4.9
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