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. M

    Integrating Fermionic fields by parts

    Homework Statement Hello there! I have been studying path integral for fermionic fields, and I don't understand one detail. I have to proove that: \int d^4x\int d^4 y\, \overline{\eta (y)}S^+_F(x-y)(i\partial\!\!\!/-m)\Psi (x)=\int d^4x \, \overline{\eta (x)} \Psi (x) Homework Equations We...
  2. J

    Subtracting object MOI from assembly to get other parts MOI?

    Homework Statement It's been ages since I have done Moments of Inertia of complex objects! :( Can anyone help?? Say you have an assembly like an airplane and you want to just get the moment of inertia(MOI) of the tail section and you are given the Mass of whole plane,mass of tail section...
  3. I

    What do macrophages do with absorbed cell parts?

    I was wondering what happens to all the "debris" that is absorbed by macrophages? Do they process them to the waste system or is it possible that they can feed them to the needs of neighboring cells? Or do these different chemical processes of eating nutrition vs getting rid of waste not mix...
  4. S

    How Do You Correctly Apply Integration by Parts to ∫-e^(2x)*sin(e^x) dx?

    Homework Statement I want to integrate ∫-e^(2x)*sin(e^x) dx Homework Equations ∫uv'dx=uv - ∫u'v The Attempt at a Solution u = e^2x du = 2*e^2x dv = sin(e^x) v = -cos(e^x)/e^x e^(x)*cos(e^x) - 2∫e^(x)*cos(e^x) dx e^(x)*cos(e^x) - 2*sin(e^x) + c The solution I have doesn't have the two in...
  5. CaptainAmerica17

    Electronics Best way to scavenge parts for a robotic arm?

    I'm a bit new to DIY robotics and for one of my first projects, I want to build a robotic arm. I'm still thinking out the plan for it, but I'm going to need to start gathering parts. Does anyone know of the best way to get parts if you don't have immediate access to a 3D printer? Does anyone go...
  6. Krushnaraj Pandya

    What is the primitive of sinx/cos^2x?

    Homework Statement ∫e^(-x)(1-tanx)secx dx 2. Attempt at a solution I know ∫e^x(f(x)+f'(x))=e^x f(x) and I intuitively know f(x) could be secx here and therefore f'(x) will be secxtanx but I can't figure out how to reach that
  7. F

    I Does measuring an atom collapse the wavefunction of its parts?

    Suppose you have an experiment that measures the property of an atom as a whole, maybe you can put it through a double-slit or measure its spin, whatever. Presumably that will collapse the wavefunction that you used to describe the atom in that experiment. Would this entail that in the process...
  8. Psinter

    Neuron parts identification question

    From post: https://www.physicsforums.com/threads/random-thoughts-part-6.875108/page-180#post-5978198 I can see there is a gray-black stuff, but inside the gray-black stuff is a shiny lit moving stuff that moves in like a frenzy. What is the shiny lit moving stuff that moves across the...
  9. T

    Why parts of the laser ray seem brighter than other parts

    Hi. When we see a laser ray, it seems that part of the ray are brighter than the other parts and they seem like they’re vibrating and moving. It also seems there are fractures in its path. I want to know why do we see like this? For example see this picture (it is from wikipedia). I circled...
  10. ertagon2

    MHB Integration by parts, Partial fraction expansion, Improper Integrals

    - check if right check if right Now, 2 seems to be the right answer for A yet when i made x=5 and subtracted new form form the old one I got a difference of ~$\frac{4}{9}$ (should be 0 obviously) I got A=2 B=$\frac{45}{21}$ C=2 How to calculate $\lim_{{x}\to{\infty}}(- e^{-x})$
  11. F

    Equivalent mass of rotating parts

    Hi everyone ! i want to find the equivalent mass of a car rotating parts and i came across this site which provides some cars formula : http://www.thecartech.com/subjects/auto_eng/car_performance_formulas.htm So far i understand almost everything until i get to the part where inertia resistance...
  12. R

    I Solving Integration by Parts for Relativistic Kinetic Energy

    Hi, I've been following a derivation of relativistic kinetic energy. I've seen other ways to get the end result but I'm interested in finding out where I've gone wrong here: I'm struggling with integrating by parts. The author goes from...
  13. sams

    I Finding Real and Imaginary Parts of the complex wave number

    In Griffiths fourth edition, page 413, section 9.4.1. Electromagnetic Waves in Conductors, the complex wave number is given according to equation (9.124). Calculating the real and imaginary parts of the complex wave number as in equation (9.125) lead to equations (9.126). I have done the...
  14. S

    Would these parts work for a "Tesla Coil" (Slayer Exciter)?

    Hello, I want to make a Slayer Exciter circuit with a Tesla Coil. I have my parts laid out, but I want to make sure that they would work before purchasing them. Off and On switch I have one 0.5'' PVC pipe I assume any would work 9v Battery I own one 9v Battery holder I own one 22k ohms...
  15. Wrichik Basu

    B Why are only some parts of this ice block cloudy?

    I had a sprain in my leg a few days back. The doctor recommended dipping my foot alternately in ice-cold and hot water to aid blood circulation. It is here that I discovered something interesting. The picture above shows the piece of ice that was put in the bucket. The above picture shows...
  16. L

    MHB Visualization of Integration by Parts

    Hello all, I am trying to understand the rational behind the visualization of integration by parts, however I struggle with it a wee bit. I was trying to read about it in Wiki, this is what I found...
  17. maistral

    A Integration by parts of a differential

    I'll cut the long story short. What on Earth happened here: I seem to be unable to do the integration by parts of the first term. I end up with a lot of dx's.
  18. Majorana

    TRAPATT diodes -- looking for sources of parts

    Hello everybody, I wish to do some experiments with TRAPATT (TRApped Plasma Avalanche Triggered Transit) diodes, but after much googling I was unable to find the name of any manufacturer of such diodes. Anybody with useful pieces of info?... Thank you! :bow:
  19. Mr Davis 97

    Integration by Parts with Logarithmic Functions

    Homework Statement ##\displaystyle \int \frac{\log (x)}{x}~ dx## Homework EquationsThe Attempt at a Solution I am a little confused about the first part. We know that the ##\displaystyle \int \frac{1}{x}~ dx = \log |x|##. So how can we proceed with integration by parts if one of the logs has...
  20. Monoxdifly

    MHB Segments in a Circle: How Many Parts Can Form & What Will It Look Like?

    If a circle has 6 segments, how many maximum parts which can be formed? I know that 1 segment makes 2 parts, 2 segments make 4 parts, and 3 segments makes 7 parts. Judging by the pattern, is the answer 22? What will the exact picture of the circle be? Thank you very much.
  21. binbagsss

    Elliptic Functions, same principal parts, finding additive C

    Homework Statement See attached. The solution of part e) is ##C=4\psi(a)## I am looking at part e, the answer to part d being that the principal parts around the poles ##z=0## and ##z=-a## are the same. Homework EquationsThe Attempt at a Solution [/B] Since we already know the negative...
  22. dlgoff

    Save on Radio Shack Parts Before They're Gone - Up to 70% Off!

    I stopped by Radio Shack and picked up some parts since they're going out of business. I bought mainly plugs and connectors but also a soldering iron and some 50 Ω coaxial cables. Normal price total would have been $104.28. Out of business price total w/tax was $30.57. They're open half a...
  23. karush

    MHB Integration By Parts: uv-Substitution - 9.2

    $\tiny{9.2}$ \begin{align*} \displaystyle I&=\int y^3e^{-9y} \, dx\\ \textit{uv substitution}\\ u&=y^3\therefore \frac{1}{3}du=y^2dx\\ dv&=e^{-9y}\, dx\therefore v=e^{-9y}\\ \end{align*} will stop there this looks like tabular method better
  24. M

    Parts of the design of an aircraft that affect the pitching moment

    If I wanted a higher value for pitching moment due to a change in pitch rate, Mq, what are some design alterations I might make to an aircraft to incorporate this. I am guessing changes to the airfoil or maybe the tailplane but I am not sure what changes you would make to get a desired result.
  25. EthanVandals

    Integration by Parts Twice: How to Solve Tricky Integrals

    Homework Statement Integrate e^3x sin x. Homework Equations uv - Integral(v du) The Attempt at a Solution I am trying to help somebody else with this problem, as I took Calculus a few years ago, but the end is really kicking my butt. I know I'm VERY close, but once I get to the second...
  26. Angelo Cirino

    I Laplacian in integration by parts in Jackson

    I am reviewing Jackson's "Classical Electromagnetism" and it seems that I need to review vector calculus too. In section 1.11 the equation ##W=-\frac{\epsilon_0}{2}\int \Phi\mathbf \nabla^2\Phi d^3x## through an integration by parts leads to equation 1.54 ##W=\frac{\epsilon_0}{2}\int |\mathbf...
  27. binbagsss

    Quantum theory, show variation of S zero, integrate by parts

    Homework Statement Hi, Please see attached. I am trying to show the second equality , expressing all as a total derivative (I can then show that ##\delta S = ##) Homework Equations See above The Attempt at a Solution So the ## m ## term is pretty obvious, simply using the chain rule. It...
  28. Maximilian Popelier

    Mechanical parts of a jet engine

    Hi guys I'm making a project about jet engine. I need to write 10 pages of the mechanical part of a jet engine. I already did it for physics. What can i talk about. I need formules en stuff in the 10 pages Ty for the help guys! Max
  29. JoeStrout

    How to simulate rotational stability of multiple parts?

    I've written a space colony simulation game called High Frontier. It correctly simulates rotational stability when most of the mass is dominated by a single large spinning part. For example, a squat cylinder will be stable, but a long cylinder will end up tumbling end over end, as shown...
  30. binbagsss

    Delta property, integration by parts, heaviside simple property proof

    Homework Statement I am trying to show that ## \int \delta (x-a) \delta (x-c) dx = \delta (-a-c) ## via integeration by parts, but instead I am getting ##\delta (c-a) ## (or ##\delta (a-c)## depending how I go...). Can someone please help me out where I've gone wrong: struggling to spot it...
  31. S

    I Integration by Parts without using u, v

    Hello, I'm currently taking calc 1 as an undergraduate student, and my professor just showed us a new? way of solving Integration By Parts. This is the example he gave" Is there a name for this technique that substitutes d(___) instead of dx? Thank you,
  32. F

    Shear force at different parts of beam

    Homework Statement i know this question can't be done(since the location of point where the tau 1 and tau2 are measured are unknown) , but i want just want to check whether my concept is correct or not . we know that the shear stress has formula of $$\tau = VQ / It$$ , the question want the...
  33. jim hardy

    Automotive Help - Can anyone identify these transmission parts?

    My transmission experience is with old Borg Warner overdrives in Fords of 1950's. I've never had apart a modern automatic transmission. We changed the oil in son's automatic transmission today, a 2001 Ford Explorer (4.0l v6 4wd) . Oil was dirty , but no bronze or metal shavings in filter just...
  34. A

    MHB Testing 3 kinds of crops of 3 each on 9 different parts of a field?

    Problem posted below.
  35. C

    I Parts per million of vapor above a liquor in a sealed jar

    How would you calculate the concentration of a vapor above a liquid in a sealed jar in parts per million? Supposing that the liquid is a 10% solution of X with known vapor pressure. We've gotten to this point: 1ppm = 1mgX/ g solution 1ppm = 1mgX/1mL solution (assuming it's water and water has...
  36. A

    I Path integral and causally disconnected parts of universe....

    One more question: it appears that portions of the universe are expanding away from us faster than the speed of light. Given this, particles in two 'parts' of the universe that are no longer causally connected should not be able to influence each other (due to speed of light constraint). So...
  37. C

    Find the real and imaginary parts of (1-z)/(i+z)

    Member advised that the homework template is required. Hey there! Need help figuring this out: Find the real and imaginary parts of \frac{1-z}{i+z} What I've tried was to notice that z\bar{z}=|z|^2, thence...
  38. Elvis 123456789

    Integration by parts and approximation by power series

    Homework Statement An object of mass m is initially at rest and is subject to a time-dependent force given by F = kte^(-λt), where k and λ are constants. a) Find v(t) and x(t). b) Show for small t that v = 1/2 *k/m t^2 and x = 1/6 *k/m t^3. c) Find the object’s terminal velocity. Homework...
  39. J

    Reconstruction of the Fourier transform from its parts

    I am using ROOT to calculate the Fourier transform of a digital signal. I can extract the individual parts of the transform, the magnitude and phase in the form of a 1D histogram. I am attempting to reconstruct the transforms from the phase and magnitude but cannot seem to figure it out. Any...
  40. L

    A Imaginary parts of amplitues (Schwartz QFT text)

    From Schwartz http://isites.harvard.edu/fs/docs/icb.topic521209.files/QFT-Schwartz.pdf p. 257 or his qft book p. 455 1. Why and how does the integral in (24.24) go imaginary, when M > 2m? Is it because the logarithms can not take negative real numbers, thus we have to switch to complex...
  41. tomwilliam2

    Laplace transform -- By parts?

    Homework Statement ##A\dot{x} + By = 0## ##C\dot{y} + Dx = 0##Homework Equations ##\int u'v = uv - \int uv'## The Attempt at a Solution This is a system of linear DE: ##A\dot{x} + By = 0## ##C\dot{y} + Dx = 0## Where the constants A-D are non-zero and x and y are functions of time. This is...
  42. C

    MHB Why does the integral of √(a² +x²) need Integration by parts?

    Why this integral $\int\left\{\sqrt{{a}^{2}+{x}^{2}}\right\}dx$ needs integration by parts? Thanks Cbarker1
  43. karush

    MHB How is Integration by Parts Applied to $\int_{0}^{\pi} x^3 \cos(x) \, dx$?

    $\Large {S6-7.1.24}$ $$ \displaystyle I=\int_{0}^{\pi} {x}^{3}\cos\left({x}\right)\,dx=12-3{\pi}^{2} \\ \begin{align} u& = {{x}^{3}} & dv&=\cos\left({x}\right) \, dx \\ du&={3x^2} \ d{x}& v&={\sin\left({x}\right)} \end{align} \\ $$ $$ \text{IBP} \displaystyle =uv-\int v\ du \\...
  44. F

    Solution to Problem 624: Moment Diagrams by Parts

    Homework Statement http://www.mathalino.com/reviewer/mechanics-and-strength-of-materials/solution-to-problem-624-moment-diagrams-by-parts First , 1st solution, the author taking moment about 2m from A? secondly, the 800Nm is clockwise moment, so it is positive? why the 2400Nm on the...
  45. S

    Why do US lamp parts use an "IP" thread ?

    Is there a reason (other than tradition) why lamps in the USA use threaded tubing that has an "IP" thread standard ? Does Europe have a better approach ? I find it irritating that the nuts and connectors in the main part of local hardware stores don't fit the threaded tubing in lamps. You...
  46. M

    A Challenge: splitting an angle into three equal parts

    I recently decided to take a whack at this problem. Came up with an interesting approach, thought it would make a good conversation topic. Anyone else tried to do this? What were your results?
  47. Electgineer99

    Understanding Integration by Parts: Exploring the Formula and Solving Examples

    |3^xlog3dxI don't even know where to start. I know that the formula is |u.dv = uv - |v.du u=3^x v=log3
  48. karush

    MHB Integrating by Parts: Solving a Sin x Problem

    \\text{w8.4.13 Integration by Parts} nmh{2000} $\displaystyle I=\int \sin\left({\sqrt{x}}\right) \ d{t} =2\sin\left({\sqrt{x}}\right) -2\sqrt{x}\cos\left({\sqrt{x}}\right)+C$ $\begin{align} \displaystyle u& = {\sin\left({\sqrt{x}}\right)} & dv&={1} \ dx \\ \\...
  49. karush

    MHB Whitman 8.4.7 integrate by parts

    $\tiny{Whitman \ \ \ 8.4.7 }$ $\displaystyle \int x \arctan\left({x}\right) \ dx =\frac {{x}^{2} \arctan\left({x}\right) +\arctan\left({x}\right) - x} {2 } + C$ $\displaystyle uv-\int v \ du $ $\begin{align}\displaystyle u& = x& dv&= \arctan\left({x}\right) \ dx \\ du&=dx& v&...
  50. C

    Integration by Parts: Solving Integrals with √(1+x^2) and x

    Homework Statement [/B] Homework Equations ∫ f(x) g'(x) dx = f(x) g(x) - ∫ f '(x) g(x) dx f(x)=√(1+x^2) f '(x)=x * 1/√(1+x^2) g'(x)=1 g(x)=x The Attempt at a Solution ∫ √(1+x^2) * 1 dx =x * √(1+x^2) - ∫ x^2 * 1/√(1+x^2) dx Further integration just makes the result look further from what...
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