Moments in equilibrium

A

annaanna

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A bit confused about what section to put this under but I really don't understand how the answer is C, does direction of the force mean the net force of weight and cable? or just cable? is the wall doing anything...? I thought the answer was A to balance it out 1709809552518.png
 
annaanna said:
A bit confused about what section to put this under but I really don't understand how the answer is C, does direction of the force mean the net force of weight and cable? or just cable? is the wall doing anything...? I thought the answer was A to balance it out View attachment 37341
Click to expand...
The only force being applied to the rod is due to Gravity which is being represented by the arrow marked "W".

The tension in the Cable is what is opposing Gravity and thereby keeping the system in equilibrium.

However, because that cable's tension is acting at an angle you must consider the components of that force in the horizontal and vertical directions.

It's vertical component must be equal and opposite to the force of gravity (acting directly downwards) but (because the tension is acting at an angle) there will also be a horizontal component of it acting along the rod towards the wall.

The reaction to that component of the cable's tension will therefore be the horizontal force provided by the wall in the direction shown by arrow C.

Hope that helps. 😊
 
Last edited:
annaanna said:
A bit confused about what section to put this under but I really don't understand how the answer is C, does direction of the force mean the net force of weight and cable? or just cable? is the wall doing anything...? I thought the answer was A to balance it out View attachment 37341
Click to expand...

Draw the free-body-diagram of the structure

1709821355417.png

Now solve for Xx and Xy by taking sum of moments and sum of forces. You will find that Xy = 0, for this SPECIAL case.
 
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