Finding Moments of a Beam: Where Did I Go Wrong?

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The discussion revolves around a static equilibrium problem involving forces and moments, specifically calculating the forces Fay and Fby. The user initially finds an impossible value for Fay, indicating a misunderstanding of the direction of forces. After reevaluating the moments about point B, they correctly calculate Fay as 15 kN but still need to clarify its direction. The importance of correctly interpreting positive and negative signs in force calculations is emphasized. The user acknowledges their mistake in mixing up the directions of the forces.
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Homework Statement


Find the Fay this is static equilibrium so ƩF=0 and ƩM=0

Homework Equations



ƩMa=0
= 2x5 + (-4x25) + (2Fby)
Fby= 45 Newtons
Using ƩFy we get Fay= impossible!

Now if take the moment about point B i get
ƩMb=0
= (4x5)+(-2x25)+2Fay
Fay = 15kN
Using ƩFy we get Fby=15Kn
Can someone tell me where i went wrong please?? I just don't get it
 
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Spakfilla said:
View attachment 45438

Homework Statement


Find the Fay this is static equilibrium so ƩF=0 and ƩM=0

Homework Equations



ƩMa=0
= 2x5 + (-4x25) + (2Fby)
Fby= 45 Newtons
Using ƩFy we get Fay= impossible!
not impossible, you get a negative value for Fay; what does that imply about the direction of Fay?
Now if take the moment about point B i get
ƩMb=0
= (4x5)+(-2x25)+2Fay
Fay = 15kN
what is its direction?
Using ƩFy we get Fby=15Kn
No, watch plus and minus signs and their meaning.
 
Thanks so much I now see my mistake. Got the directions mixed up! Damn got to be more careful
 

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