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Vish Patel
3/22/2011 10:19:31 am
Hey guys for number 59 is the force at the bottom the magnitude or what?
Chandan Yashraj
3/22/2011 01:44:58 pm
Can someone explain how to identify vectors that are parallel? I'm looking at the explanation of them on page 609 but not understanding anything from it. I get the orthogonal one though...
Vish Patel
3/23/2011 11:38:23 am
Chandan, You basically just have to plug in the vectors that they give you into the formula ((v*w)/(llvll*llwll)). Thats in the case that they give you the values for vectors v and w. If you plug it in the formula and your resulting answer is 1, then the two vectros are parallel. To find the magnitude of either one of them you just have to use the square root of a squared plus b squared, and you find a and b by using the coefficients of i and j in the equation for the vector.
Chandan Yashraj
3/23/2011 03:43:04 pm
How would you approach the first word problem in the 9.5 homework...I am getting completely lost and it's confusing me even more if I retry it (them). Please help if you can.
Chandan Yashraj
3/24/2011 11:20:24 am
So in class we had made an attempt of number 19 from 9.5, and we got the answer. I'm somewhat sure about the process of the problem, but how do you know what Va, and Vw are? You need to know these 2 to start the problem off, but I'm not clear as to how they are found...
Alex Masiak
3/24/2011 11:23:05 am
Vish
Kelly Mathesius
3/24/2011 01:54:08 pm
Chandan, you can find Va and Vw using the formula v = v (cos theta i + sin theta j). So to find Va and Vw you just plug in numbers given in the equation. So to find Va, v = 550 and theta = 225 degrees. The v is just the speed and to find theta, if you set up a graph for the vectors, you would draw a ray extending from the origin in the SW direction (or into the III quadrant). If you measured this angle, starting at 0, you would get 225 for the angle measure. Then you just plug the numbers into the equation. So Va = 550 (cos 225 i + sin 225 j). Using your calculator and after some simplifying, you get that Va = 388.909i – 388.909j. So you use the same process to find Vw. v = 80 because that is the speed. If the jet stream comes from the west, it means it is moving east. If you graph this, the ray falls right on the xaxis moving in the positive direction. So theta = 0. Then, plugging in the numbers you get: Vw = 80 (cos 0 i + sin 0 j). Then: Vw = 80 (1i + 0j). Distributive property and Vw = 80i.
Chandan Yashraj
4/3/2011 05:25:19 am
I don't know if this material will be covered in 9.6 or 9.7 later this week, but I was doing the review problems at the end of the chapter, and on page 632, number 79 and 80, what does the "x" mean?
Chandan Yashraj
4/4/2011 09:48:15 am
I guess you can just ignore that...the x's purpose is for the matrices, which will be covered in 9.7
Chandan Yashraj
4/4/2011 12:09:13 pm
Can someone go through again how to do numbers like 71 and 72 from section 9.6? It seems to be more complicated than I thought.
Kayla Simon
4/4/2011 12:43:18 pm
For 9.6 #16 and 19, how do you go about finding the other coordinates? They don't have a related example in the text.
Chandan Yashraj
4/5/2011 12:08:49 pm
@kayla
Chandan Yashraj
4/5/2011 01:55:50 pm
How would you do number 37 in 9.7, where you have to use a 3 term and a 2 term matrice?
Anika Gupta
4/6/2011 08:22:22 am
For that one, you place a zero in for the variable that appears to be missing. so it would look like row 1; 2, 3, 1 and row 2; 1, 1, 0
Justin Temple
4/6/2011 10:41:12 am
I noticed when doing the homework that for one of the problems v x w and w x v were equal but opposite. Is that true for all situations like that?
Justin Temple
4/6/2011 11:43:48 am
Wow I just realized we went over that in class and it's in the book...my bad.
Chandan Yashraj
4/6/2011 01:09:20 pm
In section 9,7 for numbers like 43 on onwards, how would you know what the adjacent sides are? For those problems it's always P1P2 and P1P3, but Mrs. Johnson was saying that that isn't the case for all problems.
Shivani D
4/6/2011 03:19:22 pm
Chandan: Mrs. Johnson said she would look at the test and let us know tomorrow.
Chandan Yashraj
4/6/2011 03:37:17 pm
@shivani
Mihir Surati
4/7/2011 09:51:51 am
Does anyone know how to do number 4 on the review sheet that Mrs. Johnson gave us today during class?
Hunter
4/7/2011 10:09:15 am
Rumor has it the test is postponed until Monday, can anybody confirm or deny?
Ashwin Chakilum
4/7/2011 10:24:01 am
@Shivani D.
Ashwin Chakilum
4/7/2011 10:26:49 am
(cont.)
Ashwin Chakilum
4/7/2011 10:31:23 am
@Hunter
Chandan Yashraj
4/7/2011 10:45:39 am
@Ashwin
Chandan Yashraj
4/7/2011 10:50:02 am
On the take home quiz, is the A coordinate the P0 in all the cases?
Ashwin Chakilum
4/7/2011 10:59:25 am
@Chandan Yashraj
Chandan Yashraj
4/7/2011 11:12:04 am
@Ashwin
Alex tazic
4/7/2011 11:24:39 am
p0 is always the point you use in both the ab and ac vectors so the a basically, its the inital
Chandan Yashraj
4/7/2011 12:34:57 pm
@Alex tazic
Alex Masiak
4/7/2011 12:46:40 pm
@ Chandan
Shivani D
4/7/2011 12:49:17 pm
I have the same question as Hunter, does anybody know if the math test is definitely postponed to Monday?
Bethany
4/7/2011 01:01:45 pm
Okay, I have the same question as Hunter and Shivani.
Justin Temple
4/7/2011 01:05:07 pm
Im really confused with the general process used to solve a work problem, specifically in 3D. Can someone help me through one, like the one on the review sheet we got today?
Christian Noblett
4/7/2011 01:39:04 pm
Heres an example from 9.5 # 31 for work problems:
Chandan Yashraj
4/7/2011 01:41:29 pm
For number 2 in the review sheet, how do you know what the units are for the work? Why is it ft lbs for that problem, but in the book work is in terms of joules?
Justin Temple
4/7/2011 01:51:00 pm
@Chandan
Alex tazic
4/7/2011 02:05:46 pm
in number two im doing the projected work equation from the book and i am getting 1800 over 29, times 12j which does not make srnse cause it says the answer is 1800/ root 29
Alex masiak
4/7/2011 02:06:53 pm
@ Justin
Alex tazic
4/7/2011 02:37:52 pm
For number 1 try making it into triangles and using law of sines anf cosines
Chandan Yashraj
4/7/2011 02:55:38 pm
If anyone has noticed....THE MATH TEST IS POSTPONED TO MONDAY! check the precalc tab if you don't believe me.
Alex: For number #1, you first need to find the equation of the 620 magnitude vector. You can set up a right triangle with the given information: an angle of 55 degrees (9035), and a hypotenuse of 620. You can then use the trig identities to find the lengths each leg using 620cos55 and 620sin55. Each leg translates to i and j in the vector.
Muhammed Alikhan
4/9/2011 10:20:17 am
Can anyone help me with #8 on the review worksheet? It asks for the direction angles, but I don't really know what that's talking about...
Vish Patel
4/10/2011 04:00:31 am
Muhammed, to find the direction angles you just have to plug in A, B, and C into the formula. There are three direction angles, one for each A, B and C. In order to find them, you just have to take the value of A, B or C and divide it by the magnitude of the entire vector. So it would be (A/IIVII) or (B/IIVII) or (C/IIVII). Once you get that, you just do the inverse cosine of your answer and then you will get the direction angles for each.
Muhammed Alikhan
4/10/2011 04:32:12 am
Oh ok thanks Vish I just forgot about taking the inverse cosine of each
Chandan Yashraj
4/10/2011 07:07:35 am
@Alex in response to Kyle
Kyle Wong
4/10/2011 09:46:18 am
Chandan, you have to use the vector method on the test. It's true you can use the law of cosines; however, Mrs. Johnson wants us to use vectors.
Chandan Yashraj
4/10/2011 10:33:45 am
@Kyle
Chandan Yashraj
4/11/2011 10:30:24 am
never mind guys...the test said different than me.
Jeff Markham
4/13/2011 12:26:36 pm
how do i get to the hippocampus thing ms johnson wants us to go to?
Chandan Yashraj
4/16/2011 04:01:37 am
@Jeff Comments are closed.

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