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Math Help - Force Vectors problem

  1. #1
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    Force Vectors problem

    Hello,

    Can someone help explain the following problem? It is supposedly a "review" question but I really have no idea where to start. Thanks.

    A force vector has a magnitude of 340 newtons (N) and points at an angle of 60.0 below the positive x axis.

    (a) What is the algebraic expression for the x scalar component Fx of the force vector? Express your answer in terms of the magnitude F of the force vector and the angle θ that specifies the direction below the positive x axis. Remember that scalar components can be positive or negative, depending on whether they point, respectively, along the positive or negative axis. (Answer using F for F and theta for θ.)

    (b) What is the x scalar component Fx of the force vector?

    (c) What is the algebraic expression for the y scalar component Fy of the force vector? Express your answer in terms of the magnitude F of the force vector and the angle θ that specifies the direction below the positive x axis. Remember that scalar components can be positive or negative, depending on whether they point, respectively, along the positive or negative axis. (Answer using F for F and theta for θ.)

    (d) What is the y scalar component Fy of the force vector?

    Any help would be appreciated and I am sure that if someone could explain parts a and b I could do c and d.

    Thanks,
    juventinoalex
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  2. #2
    A Plied Mathematician
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    Use trigonometry to resolve the magnitude/direction description into cartesian coordinates. Draw a triangle from the origin along the angle. Label sides, and see what the sin and cos of the angle give you.
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  3. #3
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    OK, I have the algebraic expression as being 340 sin 60 = 294.45 for the y which I know is correct and 340 cos 60 = 170 for the x compnent which I also know is correct. I think the thing that has me stuck is what to write in for the algebraic expression. Do they just want 340 sin 60 and 340 cos 60?
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  4. #4
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    Actually all they wanted was Fcostheta and Fsintheta. Thanks for the help though.
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  5. #5
    A Plied Mathematician
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    They're after

    F_{x}=F\cos(\theta) and
    F_{y}=F\sin(\theta).

    You already know these formulas, or you wouldn't be able to compute the components the way you did. Note: the angle is prescribed BELOW the x-axis. So that means the angle isn't 60 degrees. Instead it's what?
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