- #1
yaro99
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Homework Statement
Using the method of joints, determine the force in each member of the truss shown. State whether each member is in tension or compression.
Homework Equations
ƩFx=0
ƩFy=0
ƩM=0
The Attempt at a Solution
I got the forces at C and D by using the equilibrium equations for the entire truss:
D = 30 kN ↑
Cx = 10 kN ←
Cy = 30 kN ↓
By anlaysis of the forces at joint C, I obtained:
FCD = 10 kN T
FBC = 30 kN T
My problem is joint with joint B. Here is my diagram of its forces:
ƩFx=0: 5 - (1/√5)*FBD = 0
FBD = 11.18 kN C
ƩFy=0: FAB - 30 + (2/√5)*11.18 = 0
FAB = 20 kN T
I got FAB correct, but FBD is supposed to be 30 kN T