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Homework Help: Vector Forces Problem

  1. Sep 3, 2009 #1
    The question states:
    Use the measured angles to resolve each of the forces exerted by the strings into a z-component(Fz) and a horizontal component(FH).

    Fz = F cos Theta
    FH = F cos Theta

    Given angles and forces:

    30 deg. 270 N
    135 deg. 170 N
    240 deg. 260 N

    I am a little confused about the problem and what exactly its asking for.

    I will just show you my attempt for 30 deg. and see if it is the correct approach.

    angle 30 deg
    force 270 N
    Fz = F cos Theta = 135
    FH = F cos Theta = 234

    Is this what they mean by a Z component and horizontal?
  2. jcsd
  3. Sep 3, 2009 #2
    Resolving a vector means splitting it up into it's components. What you have is correct except you have [tex]cos\Theta[/tex] in both of them. I assume you meant the two equations to be
    [tex]F_z = Fsin\theta[/tex]
    [tex]F_x = Fcos\theta[/tex]
    You got the right answers so I guess you just meant sin.
  4. Sep 3, 2009 #3
    Ok thank you. Now that I have done this there is a second part to the question.

    Resolve FH into x- and y- components, Fx and Fy.

    Fx=FH cos Phi
    Fy=FH sin Phi

    How would I use the equations since its Phi instead of Theta. This is a 3-D problem just to make you aware. Therefore, Phi is the angle between FH and the x axis. I am not sure how to get Phi.
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