Understanding Stress: 75/Area vs 125/Area and (QA)

[Solidsam]

The problem

Why is the normal stress 75/Area and not 125/Area. They are both acting on the same axis so how do I know which one to choose?

And what does (QA) mean?

 

[pongo38]

hard to say without more context.

 

[Solidsam]

I linked the problem and how it's solved, you must have missed it so here it is again

 

[PhanthomJay]

The 75 and 125 lb loads are not acting along the same axis. The 75 lb load is in the direction of the y axis, and the 125 pound load is along the x axis. Only the 75 pound load contributes to the axial stress along the shaft. The 125 pound load produces bending and shear stresses, but not axial stresses.

 

[mink_man]

They're not acting along the same axis.