(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Hi friends, I have uploaded the problem and picture at the link below. Please take a look.

http://img64.imageshack.us/img64/4753/sam0247i.jpg

2. Relevant equations

F(vector) = F(cos[tex]\alpha[/tex]i + cos[tex]\beta[/tex]j + cos[tex]\gamma[/tex]k)

Ma = u_a(vector) [tex]\bullet[/tex] M_o (vector) = u_a [tex]\bullet[/tex] (r x F)

[tex]\bullet[/tex] is supposed to denote dot product. Sorry my latex sucks.

3. The attempt at a solution

Okay so for this problem, I currently have:

F = 30 (cos60i + cos60j + cos45k) = (15i + 15j + 21.2k)

Now I know I need to find the unit vector u, and position vector r. How do I find these? From the examples I've done, I've kinda known what to use for vectors u and r, but this example is different from the ones that I've worked on previously.

The force for this one is extending right from origin, whereas the problems I've previously worked on had forces away from origin.

So how would I find the unit and position vectors for this problem? And how can I determine the coordinate direction angles to produce the max moment and the max moment itself? Is there some sort of equation?

Thanks for your help and time. I'm not looking for answers here, but just something to get me rolling cause I'm stuck and I really want to figure this out but don't know how!

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# Calculating the moment about an axis?

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