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Method of Joints: Tension or Compression

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(a) Find the reactions A and D {see attachment for diagram}
(b) Use the Method of Joints to determine the force in each member. Indicate the magnitude of the force whether the member is in tension or compression.

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https://brainmass.com/engineering/mechanical-engineering/method-joints-tension-compression-29212

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Will apply the method of joints, using equilibrium to analyze the joints until we determine the forces in all members.

We first draw the free-body diagram of the whole truss. From the equilibrium consideration (sum of forces = 0.0, sum of moments around any point = 0.0) then:
The axial force at A .... Ax = 0.0.

Dy is the force in y direction at joint D
Dx is the force in x direction at joint D
Dx = 0.0 (this a moving joint in x direction)

Taking the sum of moments around A. ...

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