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    A light bar is held in suspension by three identical wires (see attachment). A point load of force 4W is applied to the bar at the position indicated. Find the forces in the wires
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    If onllllly I could be arsed
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    Maybe it is the wrong time of the year to be asking people to look at physics problems
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    what is W?
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    Assuming 4W is 4 times an unknown W, calling the three tensions from left to right a, b and c:

    Resolving vertically,

    4W = a + b + c

    Taking moments from A:

    4LW = 2Lb + 4Lc

    Taking moments from B:

    4LW + 2Lc = 2La

    Taking moments from C:

    12LW = 2Lb + 4La

    Simplifying:

    4W = a + b + c
    2W = b + 2c
    2W = a - c
    6W = b + 2a

    These won't solve though... grr
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    (Original post by elpaw)
    what is W?
    Sorry it is just a fixed constant. The answer should be in terms of W.
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    (Original post by elpaw)
    what is W?
    Why didn't you reply to my PM? :mad:
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    its not impossible, but there isnt a single answer

    if the tensions in the strings from left to right are x,y and z respectively, you can have any number of tensions which satisfy:

    x = 2 + z
    y = 2 - 2z
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    The wires are extensible.
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    (Original post by shiny)
    The wires are extensible.
    aaah, that compolicates the situation slightly....
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    does the load force act vertically downwards or perpendicular to the bar?
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    (Original post by elpaw)
    does the load force act vertically downwards or perpendicular to the bar?
    Straight down
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    Shiny, wanna just right the whole question out, PROPERLY - with all the info, this time though?
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    (Original post by thenarbisbanned)
    Shiny, wanna just right the whole question out, PROPERLY - with all the info, this time though?
    the question was worded poorly with not enough info anyhow this won't come up in a physics exam
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    I meant write as well
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    are the wires light too?
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    Extensible rods, which Mechanics book is that featured in? I am only a beginner... but id like to know where I have the pleasure of learning that...
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    Yes, the wire is light.
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    (Original post by CasedIt)
    the question was worded poorly with not enough info anyhow this won't come up in a physics exam
    Most questions in life won't come up in a physics exam. It doesn't mean you don't have a go at it! :rolleyes:
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    (Original post by RobbieC)
    Extensible rods, which Mechanics book is that featured in? I am only a beginner... but id like to know where I have the pleasure of learning that...
    the rod is also extensible now?
 
 
 

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