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    I'm some moment questions they ask you to find the reaction force at a hinge, what does that mean?
    As far as I know, a reaction force is an object applying an equal and opposite force on another object.
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    When the object (let's say a rod) is attached to the hinge, there is a *up* force which can be found by resolving against all the vertical components; against the weight of the rod, for example. There is also an *across* force which can be found by resolving against all the horizontal components in a similar way.

    By using Pythagoras Theorem, we can find the *magnitude* of the force at the hinge by creating a right angled triangle (with the sides equivalent to the *up* and *across* forces), and we can also find the angle that this magnitude makes with the vertical.
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    (Original post by Giant)
    When the object (let's say a rod) is attached to the hinge, there is a *up* force which can be found by resolving against all the vertical components; against the weight of the rod, for example. There is also an *across* force which can be found by resolving against all the horizontal components in a similar way.

    By using Pythagoras Theorem, we can find the *magnitude* of the force at the hinge by creating a right angled triangle (with the sides equivalent to the *up* and *across* forces), and we can also find the angle that this magnitude makes with the vertical.
    Thanks!
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    (Original post by Giant)
    When the object (let's say a rod) is attached to the hinge, there is a *up* force which can be found by resolving against all the vertical components; against the weight of the rod, for example. There is also an *across* force which can be found by resolving against all the horizontal components in a similar way.

    By using Pythagoras Theorem, we can find the *magnitude* of the force at the hinge by creating a right angled triangle (with the sides equivalent to the *up* and *across* forces), and we can also find the angle that this magnitude makes with the vertical.
    Actually one last question, if the thing hinged at an angle, do you resolve the forces perpendicular and parallel to the plane or to horizontal and vertical?
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    (Original post by eggfriedrice)
    Actually one last question, if the thing hinged at an angle, do you resolve the forces perpendicular and parallel to the plane or to horizontal and vertical?
    Since we need the magnitude in relation to the plane, I tend to do it perpendicular and parallel to the plane.
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    (Original post by Giant)
    Since we need the magnitude in relation to the plane, I tend to do it perpendicular and parallel to the plane.
    That's what I thought, but looking at my teachers hand written answer he did it the other way. :/
 
 
 
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