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Problems in Statics Involving Moments related to rigid bodies 
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#1
Sep2108, 05:14 PM

P: 47

I have a couple problems that I can't seem to get.
The first I'm really close, I can tell, because my professor did one that was similar in class. The answer the book gives is 250 lbs, I'm coming up with 225. The second I think is similar to another problem he did in class but I'm not quite sure. I'll post it in the next reply. 


#2
Sep2108, 05:16 PM

P: 47

This is the problem that I think is similar to the one labeled 3.71. I just want to know if I'm correct in my assumption the two problems have a similar premise.



#3
Sep2108, 08:15 PM

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#4
Sep2208, 02:09 PM

P: 47

Problems in Statics Involving Moments related to rigid bodies
I need help on part c of 3.71. I have the angle from b, which I believe I need to use. I originally thought that the way to set it up would be
86.2 = x(22.36)*sin(53.1) ^22.36 coming from the sqrt of 17.6^2+ 13.8^2 Any help on what I'm doing wrong would be appreciated. 


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Sep2208, 04:18 PM

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#6
Sep2208, 06:23 PM

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*I took the inverse tangent of 11.4/15.2
*The angle of 53.1 is correct; thats the answer the book got. *Why only 15.2? *Thanks 


#7
Sep2208, 06:36 PM

P: 47

If I could actually ask for help in another question, any help would be appreciated.
Excuse my chicken scratch work. I solved for the angle at which the force is acting at, which is 30 degrees in the xz plane. I solve for the actually distance from the x axis that said force was, which was about 387 mm or 100*sqrt(15). Given this I solved for the distance from the origin, 100*sqrt(19). I found my force, the set up a cross product. My answers are listed as such. I have the i vector correct, j is off by 8 (should be 22) and k is off by 1 (should be 39.1). I feel as if I'm really close to this one, was just wondering what I'm doing wrong here. 


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Sep2208, 08:19 PM

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#9
Sep2208, 08:26 PM

P: 47

I'm amazed at my ability to overlook the simple things in problems. Many thanks for your help with that.



#10
Sep2208, 11:19 PM

P: 47

In response to my above comment, I really realize that I overlook things too much. 3.94 I have the j and k of the force couple system (use the force that I obtained when breaking down the 220 N in the cross product. Duh.) Somehow I cant seem to get i. Any help would be appreciated.



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