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M1 resolution of forces

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heres a very badly taken photo im sorry, the question is
A 2 bar truss, as shown in the figure, is supporting a load of 20KN. determine the force in each bar


ive done AB, it is 28.3kN
I dont know how to do BC though even though it is probably very straightforward.
OK well the only force I see acting on BC would be the horizontal one acting to the right counteracting the horizontal leftward force put on by the above bar due to the 20kN force.

So calculate the horizontal force by AB and that should be the same as BC's force.
Reply 2
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TSR George
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Original post by RDKGames
OK well the only force I see acting on BC would be the horizontal one acting to the right counteracting the horizontal leftward force put on by the above bar due to the 20kN force.

So calculate the horizontal force by AB and that should be the same as BC's force.


the horizontal forces of AB and BC both confuses me because ive yet to see a question with just forces on the left and nothing on the right so I dont know where to start except maybe Fcos45 = x
What's F?

The way I see it is we have the force in AB and clearly it has a horizontal and vertical component. The vertical one cancels the 20kN weight and the horizontal one must be cancelled by the force in the other bar.

Reply 4
Avatar for TSR George
TSR George
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Original post by RDKGames
What's F?

The way I see it is we have the force in AB and clearly it has a horizontal and vertical component. The vertical one cancels the 20kN weight and the horizontal one must be cancelled by the force in the other bar.



ok so the answer is -20kN and I still have no idea how we get there. ive recapped on all my m1 stuff but this thing given in lecture today is the first time ive seen these questions like this
Well you know what the hypotenuse force is. You know the angle. So what's the blue horizontal arrow force?? It must be the same as the red arrow one which is the BC force.

Then the -ve is something to do with direction but it's unclear to me from what you've given on this thread.
Reply 6
Avatar for TSR George
TSR George
OP
17
Original post by RDKGames
Well you know what the hypotenuse force is. You know the angle. So what's the blue horizontal arrow force?? It must be the same as the red arrow one which is the BC force.

Then the -ve is something to do with direction but it's unclear to me from what you've given on this thread.


amazing thank you !

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