Anyone good with vector problems involving moments?

- anonymous

Anyone good with vector problems involving moments?

- Stacey Warren - Expert brainly.com

Hey! We 've verified this expert answer for you, click below to unlock the details :)

- chestercat

I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!

- anonymous

Is my method correct or was I reading the problem wrong?

- anonymous

http://www.scribd.com/doc/86313887/Problem-6

- anonymous

I don't understand what they mean by "equally inclined to the positive ends of the orthogonal axis," but your methodology looks correct and complete.

Looking for something else?

Not the answer you are looking for? Search for more explanations.

## More answers

- anonymous

You're totally wrong.... sorry

- anonymous

Just kidding. Your method is correct and you get the right answer. Congratulations.

- anonymous

@eashmore my instructor writes all of these problems and this was the practice final exam. I think he wanted to make the questions as hard as possible. He wanted us to work backwards (r crossed with F = moment, so find the components of F).
Equally inclined means this: You have an angle with the x-axis, with the y-axis and the z-axis. (Sorry if this info is nothing new to you!). A vector in 3-space has those 3 direction angles: alpha, beta, and gamma. If all angles are equally inclined, you can say:
alpha=beta=gamma = theta (we'll just use theta so as not to cause confusion).
If you square the cosine of each angle, that will equal 1.
cos^2(alpha) +cos^2(beta) +cos^2(gamma) = 1
Since the angles equal eachother (equally inclined with the positive axes, we can say:
cos^2(theta) +cos^2(theta) +cos^2(theta) = 1
3 cos^2(theta) =1
cos^2(theta) = 1/3
cos (theta) = 1/sqrt(3)
Therefore, all alpha, beta, and gamma have direction cosines of 1/sqrt(3)
So after all of that work, your unit vector will be:
(1/sqrt(3))i +(1/sqrt(3))j +(1/sqrt(3))k
Pg. 29 seems to explain this concept fairly well (see attached).

##### 1 Attachment

- anonymous

I can give you harder problems if you want to practice.

- anonymous

Well it was just the wording. Sometimes I have to read the question a few times to figure out what he wants.

- anonymous

To be fair, some other people were on here last night and had no clue what was going on. Well I finished my final today and I'm all "vectored" out.

- anonymous

Yeah that equally inclined thing it's weird. Haha I bet you'll get a good grade.

- anonymous

I will tell you what I don't get. The instructor gave 2 hours for the test. Some people finished in 50min, got up and left. Why not just sit around for the whole 2 hrs?

- anonymous

Well noboyd would notice them if they stay sit.

- anonymous

Or maybe they had to go to the bathroom =P

- anonymous

HAHAHAHAHA I have something funny to mention

- anonymous

I took multivar. calc last quarter and my teacher had us take the exams in the testing center. My classmate would sit in the testing center for like 5 hours taking her test. I asked her how she resisted going to the bathroom. She's like... I just hold it in.

- anonymous

Ohh poor girl! Five hours is insane!

- anonymous

My instructor was really tough. The exams were all application-based and it had been 5 years since I'd been into math. My dad convinced me to sign up lol.

- anonymous

I wish you could help me with multivar calc. later

- anonymous

I don't quite understand. In which grade are you?

- anonymous

I changed my mind about what field I want to go into.

- anonymous

I took 3 quarters of calc starting when I was 17 and I'm 24 now.

- anonymous

Which grade am I in? "Starting over!"

- anonymous

Sorry, but what were you studying before?

- anonymous

to get into pharmacy school

- anonymous

Did you want to be a mathematiciand and then changed your mind?

- anonymous

Nope, I am retarded at math compared to other people.

- anonymous

and now what is your major? Engineering?

- anonymous

I know you're not retarded but I can say is useful to think that haha.

- anonymous

I think civil would be a good path. And hopefully I could get a job with county... anything having to do with infrastructure.

- anonymous

Ahh yeah! I remember you told me that long time ago!

- anonymous

It's okay.

- anonymous

If I had to build a house I would call you =P

- anonymous

It would crumble LOL!!!!!

- anonymous

Hahaha "structurally unsound"

- anonymous

I'm so used to that now.

- anonymous

Do you study there ATM?

- anonymous

Please tell me when you get into statics.
I have plenty of doubts on that!

- anonymous

I'll brb... sec

- anonymous

Thanks for the explaination of 'equally inclined.' @brinethery I've never heard that expression.
Civil is a great field if you're interested in infrastructure. Everything from sky-scrapers to drainage ditches!
Keep up the great work! You're problems are always challenging and then you end up solving them before I can!

- anonymous

My teacher responded to my email this morning after I sent him the pdf file of what I wrote. He's like... no, no! Here's how you do it! Again, Jae saves the day :-)

- anonymous

what pdf?

- anonymous

Who is Jae?

- anonymous

My instructor.

- anonymous

Was your problem wrong?

- anonymous

You know the program Adobe that opens up those document files where you can only view them and do a tiny bit of editing? That's a pdf file.

- anonymous

hahaha I know what a pdf is =P

- anonymous

The original problem was wrong. But then I uploaded the revision to Scribd. The link remains the same if it's a revision.

- anonymous

I meant what was the content of the pdf?

- anonymous

ahhh!

- anonymous

I think I trashed the original, but it's wrong lol. But the current version is correct.
I thought he was saying that F sub x and F sub y were equally inclined. But he corrected me on that.

- anonymous

That is great! I wish I had teachers like him =P

- anonymous

I had one but I failed miserably in his class. Shame on me.

- anonymous

Actually he's teaching engr 106, but another instructor writes all of the exams and final exam. So that's probably why the exams are worded so strangely.

- anonymous

Thank you. I'd apreciated that!

- anonymous

k, I'll create a link.

- anonymous

I want so bad to understand Maxwell's equations, but I suck at Calculus hehe

- anonymous

Perfecto!

- anonymous

Sucks, I wish I had all the solns for at least one textbook. I don't think of it as cheating if I'm reading solutions as though I would read a textbook. It just helps to better understand things.

- anonymous

Maybe you're a different kind of learner.

- anonymous

Sorry @eashmore we can bring the convo outside of here if you keep getting pop-up messages.

- anonymous

Doesn't bother me. The wealth of notifications strokes my ego a bit. :-)

- anonymous

Hahaha I'm totally abusing the system :-). I'll try to bring it away from here.

Looking for something else?

Not the answer you are looking for? Search for more explanations.