grayfalcon89

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Everything posted by grayfalcon89

Not sure where this really fits since it's been so long that I've been here (I didn't recognize that this was a new forum until I checked the URL...), so mods - if this is a wrong forum, feel free to move it. Thank you. This fall, I'll be taking Physical Chemistry as a part of my major. My issue is that I haven't taken calculus since my junior year, when I took AP Calculus BC exam and got 5. I'm strong at mathematics but because I haven't touched it so long (I'll be junior in college this fall), I'm worried that I'll be behind in mathematics for p-chem. So, I have two books that I'm considering, and I would appreciate any feedback from people who have used it or know somebody who did. Thank you! http://www.amazon.com/Applied-Mathematics-Physical-Chemistry-3rd/dp/0131008455/ref=pd_sim_b_3 http://www.amazon.com/Mathematics-Physical-Chemistry-Donald-McQuarrie/dp/1891389564
2. Sodium acetate and pH question

Hi, This is from a part of solution from the list of problems I have to do for Analytical Chemistry class. This one line perplexes me, and I'm basically :doh:ing myself (smacking myself in the forehead..) because I can't understand it. The question is to find the fraction of association ($\alpha$) for $1.00 \times 10^{-12}$ M sodium acetate. Now, the solution says, "For $1.00 \times 10^{-12}$ M sodium acetate, pH = 7.00." When I tried to use the equation for fraction of association, I ended up as x (the variable for [bH+] and [OH-]) as zero. Something isn't right, and I wonder if this is conceptual thing that I am missing out. Sorry if this sounds like a homework. It's not. It's just one sentence that makes me confused on how you go from molarity to pH like that (and not just any pH, 7.00!).
3. Multivariable calculus for Modern Physics?

Yeah, I heard the same thing about Diff-eq (math department here tends to abbreviate the courses... not sure why). I didn't really "learn" series and sequences on Calculus II (I just learned it off from AP prep book), so I don't plan to take diff-eq. I was told that Multivariable is just extended version of Calculus I. I talked with a physics senior in my school, and he said that if I'm serious about doing something with physics, I should switch to Calculus-based physics next semester. I feel that that movement will be risky for my grades though... and the professor for Calculus-based Physics is really tough, like I feel like I would understand everything, but he would just make my life miserable with his meticulousness (I have him for my intro lab). I'm meeting with my Physics professor next Monday (hopefully) and my adviser on Wednesday. I feel that if I'm not going to do anything on physics (e.g. no modern physics), then I probably won't end up taking Calculus III because I could take something else that interests me. My professor for Inorganic Chemistry said that she learned all her math for p-chem with just stuffs from up to Calculus II, so yeah... Thank you all for the responses! This is really helpful because I don't know any physics major (and as we all know, they are all really rare...)
4. Multivariable calculus for Modern Physics?

That's what I'm worried about too. I mean, I really like physics, but I didn't want to jump into a calculus-based physics for second semester when I had a algebra-based physics for the first semester (and the professor once told me about this student who did that, and had A on the first semester - algebra-based physics and ended with C on the second semester - calculus-based physics). I'm really thinking this because as you said, Modern Physics can be a very difficult course since I'm jumping from algebra to calculus-based physics. I really think that taking calculus III won't be as helpful for p-chem because there are students in my school who took p-chem with up to Calculus II (in fact, most are) and who ended up doing fine... The problem is that I'm pre-med student, and I can't really risk doing bad on science courses for GPA. Biology is too much memorization and regurgitation for me, and Chemistry, at least from my exposure, isn't that much deep thinking (not saying Chemistry is easy but, like, it's mostly simple mathematics in an abstract concept). Physics, on the other hand, is so much fun... It's abstract and concrete at the same time? I love staring at physics problems even though they get me frustrated sometimes.
5. Multivariable calculus for Modern Physics?

That's the thing. Normally, it's Calculus-based Physics I & II, and then Modern Physics. I figured if I take Calculus III, it should help for Modern Physics even though I am just in Algebra-based physics?
6. Ideal Gas and IMF

Ah okay. Thank you all! And exam tonight.
7. Multivariable calculus for Modern Physics?

I haven't had Calculus II since my junior year in high school. I'm pretty good at math, so I pick up math easily, and I'm not too worried about multivariable calculus as long as I review some calc beforehand. My question is that I want to take it because I'm taking Modern Physics next fall. I'm in Algebra-based Physics I now, and I will move to Algebra-based Physics II next spring. Do you think this would be a good idea or just a waste of time? Also, does Multivariable Calculus help for Physical Chemistry?
8. Any good source for detailed photosynthesis/cellular respiration?

Thank you! I'll definitely check it out. My library doesn't really have "textbook" for me to borrow. I have Campbell's Biology 8th Edition at home (this is what we used for introductory level biology), and I know NIH has a free version of a biology book (forgot what it's called) on its website. I heard Karp is good but I was looking for like a website.
9. Ideal Gas and IMF

Thank you all for answers! Everything makes so much more sense now. Just curious, UC mentioned that ideal gas considers cases like low pressure and high temperature. I agree with the low pressure, but how does high temperature fit in this case as well? Or is it just a direct application of Charles's Law?
10. Acetyl CoA's relation to Glycogen

I'm not completely sure, but isn't Acetyl CoA created in the beginning of citric acid cycle? Like, would any radioactively tagged carbon in Acetyl CoA end up in the glycogen? Maybe I'm just thinking something completely odd, but my guess is that it has to do something with carbons...
11. Any good source for detailed photosynthesis/cellular respiration?

Hi, I searched for a while in Google couple months ago, but what website/link do you recommend for detailed processes for photosynthesis and cellular respiration? I had one year of college biology, but I know that what I learned for photosynthesis and cellular respiration are very condensed than what they are (I mean, we mentioned PFK and other enzymes, but still...). Do you have any good site for demonstration? Thank you~
12. Ideal Gas and IMF

Hi, I'm having hard time convincing myself to two answers from my inorganic chemistry course's last year's exam. 1. Which of the following statements are valid concerning ideal gas mixtures: (there are three choices, two of which make sense to me, but this is the one I disagree) * Each gas present in the mixture behaves independently of the others. The solution says that it is valid, but I do not agree. Like, in the textbook, it mentioned how oxygen gas would not react with water, but NH3 would readily dissolve in the water - which clearly show that gases like NH3's behaviors are dependent on other molecules. Or, am I reading something into the question? 2. Ethanol (C2H5OH) and dimethyl ether (CH3OCH3) have the same empirical formula but different molecular structures. Based on the IMF, which of the following statements would be predicted to be true? (there are five choices, but I narrowed down to two) b) Ether has a higher surface tension than ethanol. e) Ethanol has a higher enthalpy of vaporization than ether. Main confusion with this problem is that I'm not sure if dimethyl ether can exhibit hydrogen bonding or not. Like, is hydrogen bonding defined as a heteroatom having a lone pair OR is it having a heteroatom with hydrogen attached to it? If it's latter, then I assume that dimethyl ether does not have hydrogen bonding, so its IMF are lower. If not, I don't know how to distinguish them based on IMF. As far as the choices are concerned, I thought that the higher IMF, the higher surface tension, along with higher MP and higher BP. Isn't this true? I'm not sure how to understand why E is correct. I really attempted them, so hopefully you guys can provide hints to guide me to the right direction (or point out flaws in my reasoning!). Thank you!
13. FBD for Circular Motion

Actually, you just made me to understand the problem! I like the word "winch" better than the "drum." Thanks so much! :D:D:D
14. FBD for Circular Motion

Hi, I'm having a really hard time understanding this question. I am not looking for someone to show how it's done, but just help with me drawing free body diagram because it is really driving me crazy (I've spent at least 2 hours just to do that and go nowhere). Thank you! Problem: An elevator cable winds on a drum of radius 90.0 cm that is connected to a motor. (a) If the elevator is moving down at 0.50 m/s, what is the angular speed of the drum? (b) If the elevator moves down 6.0 m, how many revolutions has the drum made? My issue is that I don't understand what this "drum" is for elevator. I've never heard of it before.
15. Alpha/Beta Glucose

Hi all, I was reviewing my biology from my first year of intro biology at undergrad today, and I came across something that perplexed me. How can one go from glucose to ring-shape and thus, form alpha or beta form? I searched Google and saw the chair conformation to really see why there are alpha and beta conformation, but like, how do you form two C-O bonds to form a ring with 5 carbons and 1 oxygen? Hopefully this is clear! I'm having hard time fathoming how this occurs.
16. Involution vs. Invagination

Hi, I'm hoping that the Developmental Biology goes in here... If not, sorry. Feel free to move this. Anyway, I am reading about the frog gastrulation, and I am very confused in the difference between invagination and involution. I understand the term invagination when referred to sea urchin (i.e. it's like pinching in I think) but I guess it's hard for me to visualize the term, along with involution, in the context of frog. Also, my book (Campbell) uses the term "dorsal lip" but I can't really find "lip." Please help! Thank you very much! Sincerely,
17. Simple Machines

Thank you. What happen if you have the pulley upside down though? Like, here, this is a copy of our lab from Physics class (you can find basically on internet these days) http://weird-science.org/main/res0idt9/sitebuildercontent/sitebuilderfiles/machinewithpulleys.pdf Anyway, on the first page, (2) pulley is just upside down version of simple pulley. My physics teacher and classmate told me that this has IMA of 2. But according to not counting the string you're pulling, this IMA should be 1. So how is this 2?!?
18. Simple Machines

I'm having a test on this this week and well, I have hard time understanding this concept. #1: With pulleys, my teacher tried to explain that I can find the ideal mechanical advantage of the pulleys by counting the "number" of strands. Can anyone explain how I count the strands? Say in this website: http://www.phys.unsw.edu.au/~jw/blocks.html (i), (ii), (iii) and (iv), are the IMA 1 and 2 for first two? I don't know how to do the 3rd one and I think the last one is 6... Can anyone help me with this? It is so annoying! #2: Bicycles... Can anyone tell me how bicycle breaks down into simple machines?
19. Classwork Problem (please don't move to homework!)

What are you talking about? I clearly stated that horizontal component vector is v*cos 51. This is the "v." And as for "v" in the equation, I took the square root to get v = 11.8 m/s. And no, I said that this should not belong to homework because I'm not posting a homework and asking you to give my answers. I'm asking guide on this classwork problem that I'm not sure of and even posted what I believe is answer. It's more rational to say that it is a question about concept than simple assertion of homework.
20. Classwork Problem (please don't move to homework!)

Hi, My physics class just covered projectile motion and this problem was like the at the end of lesson problem. We get a bonus credit if we get it right! I got the answer but I want to know if this is right (I got all the other projectile motion questions right so far though). * A basketball player tries to make a half-court jump shot, releasing the ball at the height of the basket. Assuming that the ball is launched at 51.0 degrees, 14.0 m from the basket, what speed must the player give the ball? My Solution: Let the resultant vector be v. Then the horizontal component velocity vector is v*cos 51 and vertical is v*sin 51. Focusing on the vertical side: vo = v sin 51 a = 9.80 m/s^2 d = vo*t+1/2*a*t^2 derivative gives vf = vo + at Since coming back velocity is same as starting except opposite: - v sin 51 = v sin 51 + (-9.80)t - 2v sin 51 = -9.80t t = (10v sin 51)/(49) Now, horizontal: d = vt 14 = (v cos 51)(10 sin 51 * 1/49) Solving for v gives me 11.8 m/s.
21. Projectile Motion and Mass

Thanks for the feedback. Yeah, I know I should believe my results (which are usually right, assuming I followed the procedures) but I'm just not born with "physics" intuition. From my AP book, I found that: Horizontal motion: $\Delta x = v_{0x} t$ $v_{x} = v_{0x}$ $a_x = 0$ Vertical motion $\Delta y = v_{0y} t + \frac{1}{2} (-g) t^2$ $v_y = v_{0y} + (-g)t$ $a_y = -g$ So, now it hits me clearly ( ) that mass is not necessary! COOL!
22. Projectile Motion and Mass

From my lab this week, I analyzed that the projectile motion is independent from the mass of the object and that it's not a factor in any equation for projectile motion. I said this based on my lab results. But I find it difficult to believe that it's true with my eyes. I don't know.. I just feel like heavier object, like car, will have less steeper projectile motion than soccer ball. Can anyone tell me if I'm right (and that my eyes, just like in other scenarios of physics, are deceptive)?
23. DNA polymerization

Hi, I've been reviewing my knowledge for DNA stuffs, and one thing confuses me ---- DNA polymerization. I thought that DNA polymerization meant elogation of DNA in Polymerase Chain Reaction. I then assumed that this is another way of saying DNA replication. But I asked my teacher for assistance before break, and he said that it's not DNA replication, but rather, the process is called dehydration synthesis, and phosphate and sugar are involved in DNA polymerization. This confuses me because it's contradictory to what I've been reading in my review books and internet. Can someone clarify this for me? Thanks!
24. Help me

Hello, I AM going insane now because of my physics class. We're learning about Newton's Three Laws (First, Second, and Third), and frankly, I understand what they mean. But when it comes to actual mathematics, I really do not know how to do them because my teacher does not teach me well. I ask questions and all I get is some gibberish! Can anyone offer me advices on what I should do? I've read the book and took careful notes on the words AND practice problems but still, the progress is not very good. I have high A on that class but the truth is, I don't really "understand" it... I don't know... I already have a full year college calculus credit and took two years of biology and chemistry without any problem. So, what is happening to me... Help! P.S. I'm not sure if I put this in right forum.
25. scale and elevator question

@Mr Skeptic: Hmm... Falling in free fall... I'm actually not that sure. I thought it would increase but then by F = ma, a is constant in free fall (isn't it just 9.80 m/s^2)? @iNow: I get that example... It's like because of my inertia right? I mean, inertia is not a force but that's still why I have that force on other side (the one that pushes me back to the seat). @swansont: I watched a video on F = ma yesterday. It says a and F have to be in same direction or something... Anyway, I said that but I"m not sure if that's related to anything. As with what you said, so if my direction of movement and acceleration is opposite, I subtract it from 9.80 m/s^2? Thank you!! And sorry for bad explanations on problem.
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