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M3 Edexcel Statics of Rigid Bodies, Force acted on an object (sliding/toppling) watch

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    Above are the questions and the solutions from its solution bank.
    In the solutions, when working out Qa, the direction of friction is taken as downwards, and the question is solved by taking moment about point A. However what I don't understand is why when working out Qb, the direction of friction is taken as parallel to the plane, instead of going downwards to the plane like in Qa? Thanks in advance.
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    Huh? i don't see the part where they say friction acts downwards
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    (Original post by Nerrad)
    However what I don't understand is why when working out Qb, the direction of friction is taken as parallel to the plane, instead of going downwards to the plane like in Qa? Thanks in advance.
    Although the image at the top of your second attachment appears to show a force "F" acting downwards, in fact the F refers to the arrow going left from A The downward arrow relates to the Mg.

    Rather a poor diagram.
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    (Original post by ghostwalker)
    Although the image at the top of your second attachment appears to show a force "F" acting downwards, in fact the F refers to the arrow going left from A The downward arrow relates to the Mg.

    Rather a poor diagram.
    Oh it's you again . I love you man, thanks.
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    (Original post by Nerrad)
    Oh it's you again . I love you man, thanks.
    :blush:
 
 
 
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