In the pipe assembly shown, points B and C lie in the xy plane and force F is parallel to...

In the pipe assembly shown, points B and C lie in the xy plane and force F is parallel to the z axis. If a twisting moment (torque) of 50N·m will cause a pipe to begin twist­ing in the flange fitting at O or at either end of the elbow fitting at A. determine the first fitting that twists and the value of F that causes it.

Figure P4.30