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

[Spakfilla]

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

 

[PhanthomJay]

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 F_ay; what does that imply about the direction of F_ay?

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.

 

[Spakfilla]

Thanks so much I now see my mistake. Got the directions mixed up! Damn got to be more careful