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How to setup linear force equations

  1. Nov 30, 2014 #1
    A planter of mass M=3kg is hung from a rod of mass m=1kg (3/4) of the way to the end. There is a horizontal wire attached to end of the rod pulling on it with tension Ft. The botom of the rod is hinged to the wall making an angle of 60 degrees with the wall. The assembly is to remain at rest.

    1. Setup the linear force balance equations, one along each axis you choose.
    2. Choose a pivot point and setup the torque balance about that point.
    3. Solve for the tension in the wire and the two force components at the hinge.
    I know I am just blatantly asking a question but this is the final question on my homework and I do not have a single clue how to do it. If you could explain all the steps involved please.

    for the first one I tried think of it like, going down but I don't know how to get that into equations

    I really need some help on this
     
  2. jcsd
  3. Nov 30, 2014 #2

    SteamKing

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    Have you tried making a sketch of the planter, the rod, and the wire?
     
  4. Nov 30, 2014 #3
    Yes I made the sketch and I believe I have solved number 2

    0=T[Lcos(theta)]-Mg[(3/4L)sin(theta)]-mg[(L/2)sin(theta)]

    I still don't get number 1, do you know how to start number 1 once you have the sketch?
     
  5. Nov 30, 2014 #4

    SteamKing

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    Did you show the forces acting on the rod on your drawing? You are given the mass of the rod and the planter, and the tension force in the wire is to be called Ft.

    I don't understand how you could solve 2) without doing anything about 1).
     
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