Mechanics of Materials; I regarding this very fundamental problem.

[gikiian]

Why would the force P not always be equal to 60 kips?

(I mean, since the structure is in equilibrium, and the members are rigid, can't we shift the two forces of 30kips each to the line of action of force P and conclude that P is always 60kips?)

Thanks for your time.

 

[OldEngr63]

You don't know what force is supplied by the wall.

Now read what the problem asked you to find.