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Homework Help: Vectors, Components and some Horizontal Force?

  1. Feb 24, 2008 #1
    1. The problem statement, all variables and given/known data

    A mass of 100kg is suspended by two ropes that make angles of 60° to the horizontal. If a horizontal pull of 200N, in a plane perpendicular to the plane of the other forces is applied find the tension in the ropes after equilibrium has occurred.


    Answer is supposed to be: T1=T2=577N
    θ=11.5° to vertical for Fh

    T1 and T2 can be solved for using vectors but I really don't know how to make use of them.

    2. Relevant equations

    The use of the cosine and sine law as well as trig ratios and components. Some of the components would be T1h (horizontal), T1v (vertical), T2h and T2v.

    3. The attempt at a solution

    I really don't know how to incorporate the vertical force into the solution or WHERE it is for that matter and what is meant by "after equilibrium." Using the info, I know that the triangle that is formed has three 60° angles and is equilateral herewith. I can find the components and use Newton's first law to state:

    1. T2 cos 60 = T1 cos 60
    2. T2 sin 60 + T1 sin 60 = Fg

    Using substitution, I found that T1=T2= 565.8N but this is STILL the solution without this "horizontal force" and thsu incorrect. I think that equilibrium occurs when the horizontal force is equal in both directions and thus is 0N but if that's the case, why is 200N required?

    Thank you so much for any help that is given! ^^
  2. jcsd
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