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brinethery
Anyone good with vector problems involving moments?
Is my method correct or was I reading the problem wrong?
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.
You're totally wrong.... sorry
Just kidding. Your method is correct and you get the right answer. Congratulations.
@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).
I can give you harder problems if you want to practice.
Well it was just the wording. Sometimes I have to read the question a few times to figure out what he wants.
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.
Yeah that equally inclined thing it's weird. Haha I bet you'll get a good grade.
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?
Well noboyd would notice them if they stay sit.
Or maybe they had to go to the bathroom =P
HAHAHAHAHA I have something funny to mention
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.
Ohh poor girl! Five hours is insane!
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.
I wish you could help me with multivar calc. later
I don't quite understand. In which grade are you?
I changed my mind about what field I want to go into.
I took 3 quarters of calc starting when I was 17 and I'm 24 now.
Which grade am I in? "Starting over!"
Sorry, but what were you studying before?
to get into pharmacy school
Did you want to be a mathematiciand and then changed your mind?
Nope, I am retarded at math compared to other people.
and now what is your major? Engineering?
I know you're not retarded but I can say is useful to think that haha.
I think civil would be a good path. And hopefully I could get a job with county... anything having to do with infrastructure.
Ahh yeah! I remember you told me that long time ago!
If I had to build a house I would call you =P
It would crumble LOL!!!!!
Hahaha "structurally unsound"
I'm so used to that now.
Do you study there ATM?
Please tell me when you get into statics. I have plenty of doubts on that!
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!
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 :-)
Was your problem wrong?
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.
hahaha I know what a pdf is =P
The original problem was wrong. But then I uploaded the revision to Scribd. The link remains the same if it's a revision.
I meant what was the content of the pdf?
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.
That is great! I wish I had teachers like him =P
I had one but I failed miserably in his class. Shame on me.
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.
Thank you. I'd apreciated that!
k, I'll create a link.
I want so bad to understand Maxwell's equations, but I suck at Calculus hehe
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.
Maybe you're a different kind of learner.
Sorry @eashmore we can bring the convo outside of here if you keep getting pop-up messages.
Doesn't bother me. The wealth of notifications strokes my ego a bit. :-)
Hahaha I'm totally abusing the system :-). I'll try to bring it away from here.