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    Take a look at the question below:



    Okay.. as the question says, there's a tension in the string BC, but I presumed there would also be a tension in the string connected to the load at D, however in the answer they have no reference to a second tension. Why is this?
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    There is a tension in the string connecting the load to D.
    The tension in this string is 200N and this allows a vertically downward force to be applied to the bar at D.
    After that you don't bother with the tension in the string. You simply work with the force(s) applied to the horizontal bar.
    There is no need to mention a tension in the vertical string (at D). It is simply used to apply a force to the bar, then you do your statics.
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    Hmm, I don't understand. To my understanding, there is a 200N load attached to a string, but there must be a tension in the string to keep the system in equilibrium, without the load plummeting downwards.
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    The load has a weight force of 200N down and a tension up. The load is not accelerating so the tension has to be 200N. Hence, the rod has a 200N force down at D.

    They probably expect you to think this through in your head, then just note that there is a 200N downwards force at D.
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    Hmm, so if the tension is 200N up, weight is 200N down, then why is there a 200N downwards force, surely it should be 0?
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    If the string is in tension, then that means that it is pulling! So think of it as pulling up with a force of 200N at its bottom end and pulling down with a force of 200N at its top end.

    The 200N up at its bottom end supports the 200N weight, and the 200N down force at its top end applies a downward force of 200N to the bar.
 
 
 
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