Help with Number 4.16: Solving Moments

[kring_c14]

I need some help with number 4.16? well actually I just can't understand the question.. what I did is calculate all the moments with respect to A.. but I don't know if this has some relevance to the problem.. $$\sum MA= -2 (18.49) - .8 (4.5) +.8 (5.51)$$
I took the counter clockwise direction as negative... I don't have any idea what the hell I am doing...I really appreciate some help...

lots of thanks!

http://www.imagevimage.com/images/1_CCI11042007_00000.jpg

 

[kring_c14]

as for number 4.12---this is what I did... I'm really not sure if this is what the problem asks..
is this wrong?

http://www.imagevimage.com/images/1_CCI11042007_00001.jpg

 

[kring_c14]

heeeelp!

 

[kring_c14]

the answer in 4.16 is supposed to 38.4... .

 

[PhanthomJay]

I need some help with number 4.16? well actually I just can't understand the question.. what I did is calculate all the moments with respect to A.. but I don't know if this has some relevance to the problem.. $$\sum MA= -2 (18.49) - .8 (4.5) +.8 (5.51)$$
I took the counter clockwise direction as negative... I don't have any idea what the hell I am doing...I really appreciate some help...

Yes, you did pretty well...except on your last term for the positive moment you used 5.51 inches but you should have used the perpendicular distance fron the center of mass of that arm to the pivot, which is half that value.