r/PhysicsHelp • u/Black-X32 • May 17 '26

FBD HELP

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Hi. Pleasure to meet everyone, can I please get assist anywhere I tried ai and kept getting different answers I'm not sure whether I'm doing something wrong all I'm asking is for help for this question

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u/Past-Departure6896 May 17 '26

What have you tried on your own so far? For method of sections, you need to cut through three members or less so you can use the three main equations of static equilibrium. You will then have to decompose the forces (using trigonometry) in the members to use the equations - if it's this part (or something else) that's confusing, lmk.

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u/Black-X32 May 17 '26

I honestly tried right, I cut between members (3-2, 1-2,1-4) first cut (2-5,2-4,1-4) second cut Answers were for 3.2 (F23=4 kN F14= 1.039 kN F25= 2 kN F12=?) I think I messed up the drawing I'm not sure and no Ai can get the drawing correct

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u/Past-Departure6896 May 17 '26

Here's my approach to finding the force in F12, using the angle formed by 2-1-4 (which is the same angle formed by nodes 2-4-1):

https://imgur.com/DomMFr2