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Homework Help

For assistance with (but not answers to) homework problems.

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A simple reminder to all: this is the "Homework Help" forum, not the "Homework Answers" forum. We will not do your work for you, only point you in the right direction. Posts that do give the answers may be removed.

  1. Started by msetim,

    Hello, I'm writting a brand new paper to talk about "knowledge management". I have bought some papers from web, but I don't have money to buy more however I would like to read and use this (http://orgsci.journal.informs.org/cgi/reprint/2/1/88) as reference. Somebody can help me to get it or just give a way to access it as read only? Thanks in advanced

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  2. Started by witt.jana,

    Now, this is not exactly home work, as I am at university doing my second degree, but: My name is Jana and I am a science communication student with a first degree in virology and immunology. Me and my fellow students are currently creating a radio show about stem cells, and I was wondering if I could ask your views, opinions, questions or comments on the issue of stem cells, stem cell research and the application of stem cells in medicine, so we can make the show more lively by integrating other people's views. As a scientist I am probably a bit biased towards stem cells - and I also learned a lot about them, but I would like to know what do other people know or …

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  3. Does it just happen? I just don't understand how it could be efficient enough to know that.

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  4. Started by newb,

    i need help! please. how do you find the definition for this. what is the domain, the range, and the graph? sgn(x-1) - sgn(x+1)

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  5. Started by Joumana,

    hi all, I've question we have human gene (with its promoter , TE , ....ect ) which code for a certain protein inserted in plasmed of bacteria , but what happen is there was no expressing for this gene !!! ... why???? -I think that may be mRNA degrated before translation by the action of nuclease enzymes. in other words, no capping or cleavage make the mRNA exposed to 3' exonuclease & 5' exonuclease. - OR may be because there is a gene control the splicing for this gene which is not transferred to plasmed. I mean there is other gene may code for protein control splicing in specific way for exons that stop the translation or produce inactive protein. …

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  6. Started by CrazCo,

    If cells didn't have a limit to the amount of times they could divide, causing them to die, would we just live forever assuming our health was in good condition?

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  7. Started by dttom,

    My question is short, how are the normal modes of stretching of C-H bonds in benzene look like? I think there are 12 of them, my thinking is: 1) s orbital of H interact with sp2 orbital of C 2) there are 6 pairs of them 3) each pair can either exist in bonding or antibonding so (A for antibonding; B for bonding): a) BBBBBB b) BBBBBA c) BBBBAA d) BBBABA e) BBABBA f) BBBAAA g) BABABA h) AAAABB i) AAABAB j) AABAAB k) AAAAAB l) AAAAAA I don't know why, but I think this thinking is wrong, please point it out and illustrate how can I figure out the number of normal mode and how they are look like when a certain molecular is given. Thanks.

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  8. Started by sxandr6,

    f(x)=x + 4 .......x - 3 I know I need to change f(x) to y and then switch x and y. I got that far I tried to multiply both sides by (y-3) in order to solve for y, but after that I got a little lost.

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  9. Started by jake_f,

    Please point out where I got wrong. The question: At a sand gravel plant, sand is falling off a conveyor belt and onto a conical pile at the rate of 10m^3 / min. The diameter of the base of the cone is approximately 3 times the altitude. At what rate is the height of the pile changing when it is 15 meters high? My solution: Let V be the volume of the conical pile, and the height be h, and the radius, r. Given, dv/dt = 10. Since the diameter of the base is approximately 3 times the altitude, h= 6r, and r = 2.5 m h=6r dh/dr = 6 v=1/3 πr^2h v=1/3 πr^2(6r) v=2 πr^3 dv/dr = 6πr^2 dv/dt= dr/dt X dv/dr dr/dt= 10 / …

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  10. Started by CrazCo,

    let f(x) be { 3-x, x<1 { ax^2+bx, x>/ 1 if it's continuous for all x what is the relationship between a and b find values for a and b that will make it continuous and differentiable i have no clue where to even start

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  11. Started by jake_f,

    Actually, I just have some doubts with my experiment result. The equation for the reaction, C7H6O3 + C4H6O3 -> C9H8O4 +CH3COOH I started off with 2.42g of salicylic acid (C7H6O3) which is about 0.175 mole of it. By right, based on the equation, one mole of salicylic acid should yield one mole of aspirin (C9H8O4). So 0.175 mole of Aspirin is expected at the end of the experiment. And the expected mass of aspirin should be 3.15g. But at the end of the experiment, I only got 1.1g of aspirin. Which when calculated in percentage yield, is only 34.92%. So should I presume that I made some mistake during the course of the experiment? When I asked my lectur…

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  12. Started by jake_f,

    Leukocytes is divided into two groups, Granulocytes and Agranulocytes. I know that the DNA is used for amino acid sequences of the proteins and enzymes. The question I would like to ask: Why do Granulocytes/ Agranulocytes have a high concentration of RNA? I also know that there are the messenger RNA (mRNA), ribosomal RNA (rRNA) and transfer RNA (tRNA). I know their functions too. But the reason is I don't really know why the Leukocytes must have a high concentration of RNA. Is it because of the white blood cell function? Please enlighten me.

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  13. Started by Asian,

    Hey guys this is my first post. Im having trouble with 3 questions on my chem lab. The first question is discuss the differences in conductivity between glacial acetic acid, 6 m acetic acid, and 0.1 m acetic acid. the second question is how do organic solids and liquids rate as electric conductors.. lastly how can you account for the fair and poor conductors of electricicty.. Much help is appreciated, but only please respond if you know the answer. Thanks!

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    • 21 replies
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  14. Started by serena,

    encased him in carbonite! He should be quite well protected. ... Assuming he survived the freezing process or is this person trying to sound smart? Isn't carbonite an explosive? I am confused what he is saying.

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    • 9 replies
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  15. Hey this question has me stumped and I could really use some help: What is the activity of liquid water in a multicomponent system in which the vapor pressure of water is 748.2 mmHg at 100.0 degrees Celsius? That is all the information given. I think I am probably missing something obvious here, but every equation I have to find activity requires some other info, ie mole fraction or partial pressure. Any help will be greatly appreciated. Thanks, RB

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  16. Started by mike2345,

    Hello, this is my first time posting:-) I have a question about conversion. I'm doing grade 8 science and in my book it says that the unit of "cc" is the same as "mL". This is all the info they give me. Then I'm asked to convert this value: 100 microL to cc? I have no idea how to do this so I looked in the answer key and the answer is: 0.1mL=0.1cc. Would someone be willing to explain the how and why? It would be greatly appreciated!!!

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  17. Started by Mashfiq,

    My project is to write an essay about a boulder. I can put the boulder anywhere and I decided to put in the Four Corners. Now I have to write about what it was like for the boulder 1,000,000 years ago, 100,000 years ago, 10,000 years ago, 1,000 years ago, and present time. Can any give me some information of the Four Corners in those times? All I need is the information. I will write it out in my own words and create similes and metaphors with it. (Because it's an ELA project.) Also, when you give the information, it would have to be from a 100 meter distance of the boulder.

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  18. Started by phyuk2008,

    Question: What is the coordination number of (a) Cadmium and (b) oxygen and what are the geometrical arangment around cadmium and oxygen? Answer: cd = 4 o = 4 Question: determine the number of cadmiun and oxygen atoms in the structure, then determine the emperical forumla of the compound and the number of forumla units in the unit cell Answer: cd = 4 o = 4 emperical forumla - CdO How is the last part worked out? Question: Calculate the density of cadmium oxide Answer: Molecular weight = 128.4104 g/mol Avogadro's number = 6.0220x10^23 what is the unit cell dimesions? Is it Cd to Cd measurement?

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  19. How are they able to access different parts of it to do different things?

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  20. Started by jsnts,

    I am having some problems with determing the cells concentration. To start i have some cells with a concentration of 9.7 x107/ml. I took 2ml of these cells and added 1ml of media to them. What is the concentration? If i then take 1ml of the above diluted cells and add a further 0.5ml of media what is the concentration of these cells now? jay

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  21. Started by hipolito201,

    I am having some trouble with this question. To solve the problem below, you must write clear and convincing justification for accepting one of the possible answer choices as best or most appropriate and for rejecting each of the other choices as less appropriate. Your reasons for rejecting choices are just as important as your reasons for choosing the best answer. 1. Although water is a small molecule, it has some properties characteristic of a large molecule. Why isn't this behavior a contradiction? a. Hydrogen bonds between molecules last only for a very short period of time. b. The small water molecules for hydrogen bonds between many individual molecules. …

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  22. Started by sxandr6,

    e^x+e^-x=5 When I first tried to solve this I tried to take the natural log but that ends up cancelling the x's out. Then I tried to square both sides but I think I messed up squaring the left half of the equation. I ended up with: e^2x+e^x+2e=25. Thoughts?

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  23. Started by DJBruce,

    Here is a question from my physic's problem set. I was wondering if my solution is correct. Question: How much work will Madison have to do to push DJ up a 22 degree ramp that is 6m long. DJ has a mass of 77.2 kg and a coefficient of friction is .29. First assume that she pushes at a constant velocity then solve again for an acceleration of 1m/s/s. My solution is that work is equal to the change in energy. [math]w=\Delta E[/math] At the beginning of the hill there is no kinetic energy and no gravitational potential energy. At the top of the hill all the energy is gravitational potential energy so the change in energy is: [math]\Delta E=mg\Delta y[…

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  24. Started by froston,

    Hello. This is a question on my latest Calculus assignment: Let f: R --> R be a function, and let a not equal zero. Suppose f is differentiable at a. Evaluate the following limit: lim x-->a of (see attached image). Express your answer in terms of f'(a). Basically I'm having trouble understanding the third roots in the denominator, and how I am supposed to tackle this question. Any push in the right direction would be greatly appreciated.

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  25. Started by xami,

    Hey =}, Im new to the forum so hi eveyone! Im studying the biology,chemistry and physics at college so i hope to learn a lot from here and also get some help please. At the moment we're learning about ions and bonding, we've been given a peice of homework where we have to write down the resulting compound of two ions where the total charge will be zero.. Im really quite stuck with this so if anyone could help me out that would be cool. one of them is: Na1+ and Cl1- would this just end up as NaCl cause the + and - cancel each other out? And if that is the right answer am i working it out rite? Another one is NH4[math]^{1+}[/math] and NO3[math]^{1-}[/m…

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