MecMovies 4.0 : M5.3: Deformation of a Compound Axial Member

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Note: Assume a positive internal force (i.e., tension).

The figure shows the free body diagram of the compound axial member with respect to the joints B and C. The free body diagram cuts through member 1. The x axis is taken along the common axis of the members. The y axis is taken perpendicular to the x axis. The load at C is P which equals 50 kilo newtons in the positive x direction and the axial force in member 1 is F subscript 1 in the negative x direction.

Cut a free-body diagram $(FBD)$ through segment $(1)$ .

Sum the forces acting in the $x$ direction.

$\sum_{} F_{x} = - F_{1} + 50 kN = 0 ∴ F_{1} = 50 kN$