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Homework Help: Tension questions (string)

  1. Oct 6, 2011 #1
    1. The problem statement, all variables and given/known data

    2 questions:
    a) Discuss whether the tension is the same throughout two wires, one of which has twice the diameter of the other, which are joined end to end and hung vertically to support a load.

    and when supporting a heady chain hanging vertically.

    b) Framed picture of weight 50N is to be hung on a wall using a piece os string. String tied to two points, 0.6m apart on the same horizontal level on the back of the picture. Find the tension in the string if it is 1m long, 0.66m long.

    2. Relevant equations


    3. The attempt at a solution

    a) Really don't understand... both should be equal? There's no reason for them to be unequal just because of size difference?

    b) 50/2 on each?? Really confused how horizontal tension correlates the the upwards tension of holding up the weight of the picture
  2. jcsd
  3. Oct 6, 2011 #2


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    Staff: Mentor

    For (a), what happens if the wires are made of some real material with mass?

    For (b), draw a Free Body Diagram for the system. Identify the forces acting and their components.
  4. Oct 7, 2011 #3
    The mass of the wires is small enough to be neglected.

    EDIT: I don't know what forces to draw on the free body diagram. Weight of 50N downwards... then? 2 25N's on each pin?
  5. Oct 7, 2011 #4


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    Staff: Mentor

    Then you should neglect their geometry, too :smile:
    You should take a look at your notes or course materials to see what sorts of forces are involved, and perhaps some examples of FBDs. There are lots of examples and tutorials on the web, too. For example:

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