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Homework Help: Calculate the net force acting on the object in the diagram

  1. Aug 30, 2016 #1
    1. The problem statement, all variables and given/known data
    Calculate the net force in Diagram B.
    2. Relevant equations
    Sine Law: sin a/a = sin b/b = sin c/ c
    Cosine Law: c^2 = a^2 + b^2 -2ab*cos(c)

    3. The attempt at a solution
    c^2 = (2N)^2 + (17)^2 -2(2)(17)*cos(45)
    = 16 N
    sin b/ 17N = sin45/16N
    = 49 degrees

    Fnet = 16 N (W 49 degrees N)

    I am really confused with this unit. I don't know if I did it right, but I would appreciate feedback on where and how i went wrong.

  2. jcsd
  3. Aug 30, 2016 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper

    A simpler way to find the net force of two or more vectors is to decompose each vector into its x and y components. Once that is done, the individual x and y components are added together algebraically, and the sum of these components gives you the component of the net force, or the resultant.

    In b) above, the 8 N force has components of (0, 8) while the 10 N force has components (0, -10). The 17.0 N force can be converted to its components by completing the 45° triangle shown. Remember, a horizontal component pointing East is positive.
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