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    • Thread Starter

    The diagram shows a simple model of a crane. The structure is at rest in a vertical plane. The rod and cables are of negligable mass and the load suspended from the joint at A is 30N. (See attached for diagram)

    ii) Calculate the forces in the rod and cable 1 and state whether they are in compression or in tension

    I know the force in the rod is compression and the force in the cable is tension,
    but how would I go about answering this question?

    I know it's probably an easy question, but I can't for the life of me understand mechanics. Any help will be greatly appreciated
    Attached Images

    At point A, there are three things providing a force - cable 1, cable 2 and the rod. Since the system is at rest, all the forces must be equal, so that the horizontal and vertical components balance out.

    Cable 2 only has a vertical component, which is 30N acting down, and this must be balanced by the vertical component of the rod and cable 1 which are both acting up. Also, the rod and cable 1 have horizontal components, in opposite directions, and these must both be equal. If you write out these equations, then you should be able to solve them simultaneously to find the forces in the rod and cable 1.
    • Thread Starter

    Thank you very much
    I'm ecstatic I managed to arrive at the correct answer (eventually)
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