- #1

yaro99

- 75

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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

ƩF

_{x}=0

ƩF

_{y}=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 ↑

C

_{x}= 10 kN ←

C

_{y}= 30 kN ↓

By anlaysis of the forces at joint C, I obtained:

F

_{CD}= 10 kN T

F

_{BC}= 30 kN T

My problem is joint with joint B. Here is my diagram of its forces:

ƩF

_{x}=0: 5 - (1/√5)*F

_{BD}= 0

F

_{BD}= 11.18 kN C

ƩF

_{y}=0: F

_{AB}- 30 + (2/√5)*11.18 = 0

F

_{AB}= 20 kN T

I got F

_{AB}correct, but F

_{BD}is supposed to be 30 kN T