Hi all,I just started to learn mechanics so please forgive me if i ask something elementary.I have an example from Egor P Popov's Engineering mechanics of solids.(Please refer attachment and sorry about quality of drawing).(adsbygoogle = window.adsbygoogle || []).push({});

This is a problem of a pin joint system subjected to vertical load that acts at point B.Since the pin joint system cannot allow x or y movement there should be reactions at A and C which are resolved into their horizontal and vertical components.For determining their value the moment about the point C and A are taken to zero ,This is where I got stuck,

I cite the step in the book

ƩMc=0 => FAx*(a+b)-P*c

ƩMa=0 => P*c +FCx*(a+b)

What happened to the y components of the reactions at A and C.Why FCy and FAy are not taken,Is that because the force applied is vertical ?.I am self studying so I cannot clarify this with someone.I know this is elemantary but pls help me..

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# Moment problem

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