parts Definition and 838 Threads

In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, 10−6), parts-per-billion (ppb, 10−9), parts-per-trillion (ppt, 10−12) and parts-per-quadrillion (ppq, 10−15). This notation is not part of the International System of Units (SI) system and its meaning is ambiguous.

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  1. C

    How to Integrate arccos x by Parts?

    Could som1 please help me integrate arccos x by parts. I've done examples using integration by parts but they were all some form of multiplication, ie y = xe^x, y = x sin x etc. I'm really unsure where to start with this problem :confused:
  2. L

    I feel like I waste too much time on the wrong parts of lab reports

    I feel like I waste too much time on the wrong parts of lab reports... So I have a tendency to write a ton in my lab reports in the theory sections...we're talking 5-6 pages or more on theory. I enjoy doing this because it gives me the chance to kinda explain the concepts in my own words to...
  3. P

    Cyclic Functions and Integration by Parts: Where Did I Go Wrong?

    Why is it that when I do integration by parts on cyclic functions such as (sinx)e^(inx), I get a trivial answer like C=C, C is a constant Have I done something wrong or are there other methods of doing those integrals?
  4. R

    Current connecting two parts of a circuit

    in the diagram below Io is zero. But i can't figure out why. Can anyone explain this to me.
  5. Y

    News Meanwhile, in other parts of the world

    http://www.pbs.org/mediashift/2006/09/digging_deeperjournalist_paint.html" http://www.rsf.org/article.php3?id_article=18768" http://www.washingtonpost.com/wp-dyn/content/article/2006/08/26/AR2006082600297.html" I contend that for international affairs, there is an undeniable direct...
  6. F

    Solving an Integral with Integration by Parts

    hello could someone give me a pointer here. this integral ∫ln(x + c)dx my guess is, by integration by parts (ab)' = a'b + ab' ∫ba = ab - ∫b'a so here a = ln(c + x) b = c + x a' = 1/(c + x) b' = 1 ab = (c + x)*ln(c + x) and ∫b'a = ∫ ((c + x)/(hc + x)) dx = ∫dx = x...
  7. S

    Integration by Parts: Solve \int (xe^-^x)dx

    hi..im new to this topic..can someone check to see if this is right? \int (xe^-^x)dx = \int udV = uV - \int Vdu =x(-e^-^x)- \int -e^-^x =-xe^-^x-e^-^x+C thanks
  8. K

    Can I produce electricity by using permanent magnets with no moving parts?

    Is it possible to produce electricity by using permanent magnets with no moving parts? I believe that is possible. Because AC current produced by moving armature or copper wire or some other metal in magnetic field. Then without moving wire it should produce DC or some kind of electron flow...
  9. maverick280857

    Momentum Operator Integration by Parts

    Hello I am teaching myself Quantum Mechanics from Griffiths. I have run into a mathematical problem which I need help with. As I have found no convincing answer, I am posting all the details here. Ref :Section 1.5 (Momentum) in "Introduction to Quantum Mechanics (2nd Edition)" by David J...
  10. A

    Why do we feel heavier or lighter at differenthis parts of the lift?

    Hi, i am currently doing a project on these questions. 1)why do we feel heavier when the lift startes to move up? 2) why do we feel normal in the middle? 3) why do we feel lighter when the lifts comes to a stop? although i know that the three laws of Newton is somehow related to...
  11. C

    Can I use integration by parts recursively on this?

    Can I use integration by parts recursively on this? \int (xe^x)(x+1)^{-2}
  12. S

    Integration by parts (Laplace transform)

    First off, I hope these images show up - I don't have time to figure out this latex stuff atm, so it's easier just to throw the formulae together in openoffice. I'm working on the Laplace Transform for http://home.directus.net/jrc748/f.gif Which is obviously...
  13. G

    Integrate by Parts: Rules & Tips for (1/x)(e^-cx)dx

    Hi Can anyone pls suggest the trick to do integration by parts such as: Intergration {(1/x) (e^-cx) }dx. Which function normally we should take as first and second function. Is there a rule to decide on it. Plz reply thanks
  14. benorin

    Real & Imaginary parts of a finite product

    So I'm trying to work-out the real and imaginary parts of a finite product, put P_n = \prod_{k=1}^{n} \left( x_k + iy_k\right) where the x's and y's are real numbers like you would expect.
  15. R

    Integration by Parts: Struggling with e^xcos(x)dx

    I'm kind of lost on where to go next with this integration by parts problem. I have to integrate e^xcos(x)dx. I've gotten as far as one step of integration by parts, but I can't understand how this will help. It seems I'll just be going in circles. I have: e^xsin(x) - int(e^xsin(x))dx...
  16. M

    Solving Integration by Parts Problems

    Okay, so here is the problem I have, which I am getting tripped up on for some reason: a) Use integration by parts to show that \int_{a}^{b} f(x) dx = bf(b) - af(a) - \int_{a}^{b} xf'(x) dx this was pretty easy, just regular old integration by parts with limits of integration. b) Use the...
  17. J

    Can something be more than the sum of its parts?

    Here's one for you: Can things be more than the sum of their parts? I'm going to share my answer later but for now I'm interested to here your thoughts. If you stop and think about it, it gets really tricky. Enjoy.
  18. U

    Complex Function: Real & Imaginary Parts, Square, Reciprocal & Absolute Value

    I am to find the imaginary part, real part, square, reciprocal, and absolut value of the complex function: y(x,t)=ie^{i(kx-\omega t)} y(x,t)=i\left( cos(kx- \omega t)+ i sin(kx- \omega t) \right) y(x,t)=icos(kx- \omega t)-sin(kx- \omega t) the imaginary part is cos(kx- \omega t) the...
  19. C

    Medical A Single Memory Is Processed In Three Separate Parts Of The Brain

    Article below.
  20. P

    Integrate by Parts: Solving x^13cos(x^7)dx

    Integration by parts :( hi I have been trying this question for quite a while now and am unsure of what to do. Any help would be apprectiated. Integral x^13 cos(x^7) dx I know you have to use integration of parts. Here is what i have done so far: let U=x^3 dU =13x^12 dx dV=cos(x^7)...
  21. Q

    Integral of x(ln x)^4: Steps & Solution

    Does the integral of x(ln x)^4 = x^2/x(ln x)^4 - x^2(ln x)^3 + 3/2 x^2 (ln x)^2 - 3/2 x^2(ln x) + 3/2 x +C ? Or did I do something completely wrong? Sorry I didn't show my work, it would probably take me 30 mins to type it up here.
  22. J

    What is the difference between integrating by substitution and by parts?

    integration by parts?? just trying to figure out this integral int(x^2 (1+x^3)^4 dx) when i integrate by substitution i get anti deriv... 1/15 (1+x^3)^5 which is not the same (but close when u plug in values of x) to 1/15*x^15 +1/3*x^12 + 2/3*x^9 + 2/3*x^6 + 1/3*x^3 am i going about...
  23. Y

    Solving Integration by Parts: Stuck on \int \sqrt{9-x^2}dx

    I've got a simple, at least it seems so; \int \sqrt{9-x^2}dx I MUST solve it "by parts" (withtout trigonometric substitutions), but I'm stuck. If i choose u = (9-x^2)^(1/2), du = -x/((9-x^2)^(1/2)), dv = dx, v = x. I then have; x\sqrt{9-x^2} + \int \frac{x^2dx}{\sqrt{9-x^2}}...
  24. R

    Understanding Integration by Parts: A Quick Guide for Beginners

    this no homework, but nevertheless can someone hint me how this integration by parts works? \int {d^4 } x\frac{{\partial L}}{{\partial \left( {\partial _\mu \phi } \right)}}\partial _\mu (\delta \phi ) = {\rm{ }} - \int {d^4 } x\partial _\mu \left( {\frac{{\partial L}}{{\partial (\partial...
  25. L

    The temperature of different parts in a flame

    We had a laboration where we did some temperature measurments on a flame and wrote a report on this. We got it back and were told to explain more deeply why we had a temperature maximum at a certain point. What happened was this. We started to meassure on the point located preciecly above the...
  26. wolram

    Baby Parts for Sale: Unimaginable Horror

    http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2003/05/18/worg18.xml&sSheet=/portal/2003/05/18/ixporta Can you imagine this ? I was lost for words, the slave trade was bad enough, but this, if true, and these," things", are found guilty, they should not be allowed to live.
  27. K

    Real and Imaginary Parts of z+(1/z) - Have I Got This Right?

    Hi there have i got this right if someone could check please? z=x+\imath{}y Find the real and imaginary parts z+(1/z) sub x+\imath{}y + \frac{1}{x+\imath{}y} if we multiply by x+\imath{}y and i get as the real part as x^2-y^2+1. Have i got this right? Thanks in advance
  28. K

    Real & Imaginary Parts of z+(1/z) in x+\imathy

    z=x+\imathy Find the real and imaginary parts z+(1/z)
  29. N

    Integration by Parts Contradiction

    Ok guys, this is my first post. Please go easy...:redface: This question is from Morris Kline's Calculus: An Intuitive and Physical Approach and unfortunately there aren't solutions for all questions (really annoying). I'm not even sure if this counts as a contradiction but anyway: Let...
  30. Z

    Integration by Parts: Assigning u & dv with LIPATE Rule

    Hi, I'm a bit confused as to what I should assign u and dv in this integration by parts: ln(1+x^2)dx I remember a general rule called the "LIPATE" rule... which is basically Logarithms, inverse trigs, poly, algebra, trig, then exponentials... Now... would I assign u = ln(1+x^2)? and...
  31. K

    Continuous and discreet parts of an electromagnetic wave

    I'm just a hobbyist in things quantum and in the course of my reading, I have found it a bit confusing figuring out which parts of quantum theory deal with finite numbers of discreet values and which parts require continuums. For example: Last night I was reading up on qbits and in the course...
  32. C

    2 Parts of Thermodynamic Homework, help Please

    Ok, the first question is this: It asks me to show that the following relation holds for a reversibe adiabatic expansion of an ideal gas: T/P ^(1 - (1/Gamma)) = constant Where Gamma = the ratio of: C_p/C_v the specific heats with constant pressure and volume, respectively. I...
  33. G

    Struggling with Integration by Parts? Try a New Approach with Secant Functions!

    Integration by parts... I just started Calc. II and though I struggle a bit, it's fascinating. I have been fooling with a problem lately...one of those standard problems that professors like to assign, and it usually appears in calculus texts: Have ya'll ever done integration by parts with...
  34. T

    Compositions into relatively prime parts

    Hello. I was reading a journal and an interesting problem came up. I believe the journal was in the American Mathematics Society publications. Well, here's the statement. "For all integers, n greater than or equal to 3, the number of compositions of n into relatively prime parts is a...
  35. Reshma

    Evaluating the Second Term of Integration by Parts for $\delta (x)$

    Show that x \frac{d(\delta (x))}{dx} = -\delta (x) where \delta (x) is a Dirac delta function. My work: Let f(x) be a arbitrary function. Using integration by parts: \int_{-\infty}^{+\infty}f(x)\left (x \frac{d(\delta (x))}{dx}\right)dx = xf(x)\delta (x)\vert _{-\infty}^{+\infty} -...
  36. I

    Understanding Big-Oh Problems with Two Parts

    I'm having a problem with a Big-Oh problem, and I think it's more that I'm not understanding what the problem is asking and that I'm not completely understanding the definitions. There are two parts of the problem: Here is the problem verbatim...
  37. A

    Integration by Parts in Several Variables

    My professor gave me the following formula for integration by parts in my multivariable calculus class. He said that we wouldn't find it in our book, and he didn't provide a proof. I have tried to work through it, but I am still left with one question: Why is it necessary that the curve is...
  38. RadiationX

    Integrating $\int_0^{\sqrt{6}}e^{-x^2}\frac{x^2}{2}$: U-Substitution or Parts?

    \int_0^\sqrt{6}}e^{-x^2}\frac{x^2}{2} should i use a u-substitution or integration by parts?
  39. S

    Building a Small Jet Engine: Experiences & Parts

    Has anyone here ever built a small Jet engine? Just generally interested in how you did it and from what parts thanks
  40. wolram

    The island is big and wooded in parts, How do they survive?

    A group of ten to twenty people are ship wrecked on a desert island, they have basic hand tools and food and water that will last for two days, no one knows they survived the ship wreck, so no chance of rescue. The island is big and wooded in parts, How do they survive?
  41. Y

    Can Integration by Parts Lead to Errors?

    It's not homework, but i think it can make someone think a little. \int\frac{dx}{x} Take it by parts. If you'll be as careless as me you can make a discovery :smile:
  42. T

    How does integration by parts work?

    Integration by parts HELP ! Ok to be honest with all of you reading this post, i just don't understand how integration by parts work. Can someone please explain how it works? I have looked on the internet for help reading through all the notes but i still do not understand. So please somone...
  43. Omegatron

    Dead battery indicator with minimal parts

    I need to make a battery monitor with minimal parts. A green LED should be lit during normal operation. The device has two batteries (designed for 9V, but it could probably use others) in a split supply (-9, 0, +9). I need to monitor BOTH batteries, and have the green light go out and a...
  44. C

    Ultrasonic welded plastic parts design

    Recently i got an offer from a company which asked for finite element analysis and design of ultrasonic welded plastic parts. I didn't know that but nevertheless i want to study that. Can anybody help?
  45. R

    Integration by Parts of <C> i just cannot do

    Can anyone outline, and this is a rather large request, the step by step integration by parts for <C>? This is not a homework question but more something i need to be able to do on tuesday for my final, and have been trying to do for two days.
  46. R

    How do I solve INT x sec^2x dx using integration by parts?

    show that INT x sec^2x dx = pi/4 - ln2/2 (between pi/4 and 0) pls help i don't know where to start i know it is integration by parts - just don't know how i should rearrange it. thanks
  47. C

    Integration by Parts: Solve x^2exp(-3x)dx

    hi guys just doing some revision and I am stuck on this question *integral sign* x^2 . exponential ^ -3x . dx I know i have to use integration by parts, but i just can't seem to get it out any ideas? thanx
  48. D

    And we have successfully proven the integration by parts formula!

    If f(0)=g(0)=0, show that \int _0 ^a f(x) g ^{\prime \prime} (x) \: dx = f(a) g^{\prime} (a) - f^{\prime} (a) g (a) + \int _0 ^a f ^{\prime \prime} (x) g (x) \: dx I know I need to use integration by parts, but I'm having a hard time figuring out the right choice of u and dv. What I do...
  49. tandoorichicken

    Integration by Parts: What's the Sign of that Last Term?

    I forgot a little detail in the integration by parts formula Is it \int u \,dv = uv + or - \int v \,du I don't remember if its plus or minus...
  50. O

    Particles Mass: Sum of its Parts?

    I used to be an avid reader on the subject, however with age I have lost some of the finer details. I was thinking back upon what I learned the other day and I was wondering if I had recalled correctly that a particles mass is less than the sum of its parts. Can anyone here tell me if this is...
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