Help with Number 4.16: Solving Moments

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The user is struggling with problem 4.16, specifically in calculating moments with respect to point A. They have calculated moments but are unsure of their relevance to the problem and express confusion about the question. A response indicates that the user is close to the correct solution but made an error in the last term by using the wrong distance for the positive moment. The correct approach involves using the perpendicular distance from the center of mass to the pivot point. The discussion highlights the importance of accurately determining distances in moment calculations.
kring_c14
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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!

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heeeelp!
 
the answer in 4.16 is supposed to 38.4... .
 
kring_c14 said:
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.
 

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