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    A rigid body ABC consists of two uniform rods AB and BC, rigidly joined at B. The lengths of AB and BC are 13cm and 20cm respectively, and their weights are 13N and 20N respectively. The distance of B from AC is 12cm. The body hangs in equilibrium, with AC horizontal, from two vertical strings attached at A and C. Find the tension in each string.

    I was thinking of taking moments but dont know how to bring tension into the equation.

    This is from OCR june 2002 Q3.

    Any help would be appreciated
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    (Original post by Freakonomics123)
    A rigid body ABC consists of two uniform rods AB and BC, rigidly joined at B. The lengths of AB and BC are 13cm and 20cm respectively, and their weights are 13N and 20N respectively. The distance of B from AC is 12cm. The body hangs in equilibrium, with AC horizontal, from two vertical strings attached at A and C. Find the tension in each string.

    I was thinking of taking moments but dont know how to bring tension into the equation.

    This is from OCR june 2002 Q3.

    Any help would be appreciated
    Remember that the tension is still a force that acts on the rods, pulling them up at A and C. If it helps just ignore that they're tension and that all it is are 2 individual forces pulling up on the rods. And since it is equilibrium you know that the anticlockwise and clockwise moments must be equal.
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    (Original post by dknt)
    Remember that the tension is still a force that acts on the rods, pulling them up at A and C. If it helps just ignore that they're tension and that all it is are 2 individual forces pulling up on the rods. And since it is equilibrium you know that the anticlockwise and clockwise moments must be equal.
    so the tension is a force pulling up at A and C? why is it pulling up? i thought it would act up and down the rod?
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    (Original post by Freakonomics123)
    so the tension is a force pulling up at A and C? why is it pulling up? i thought it would act up and down the rod?
    Think of it this way:

    The rod has a weight and pulls down on the string, trying to pull the string down with it. As a result the string pulls back up on the rod trying to keep the rod up with it. These forces are all relative to the rod, so the force of the rod trying to pull the string down is irrelevant.
 
 
 
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