# What is Diagrams: Definition and 689 Discussions

A diagram is a symbolic representation of information using visualization techniques. Diagrams have been used since ancient times on walls of caves, but became more prevalent during the Enlightenment. Sometimes, the technique uses a three-dimensional visualization which is then projected onto a two-dimensional surface. The word graph is sometimes used as a synonym for diagram.

View More On Wikipedia.org
1. ### Engineering How Do You Calculate Values Using pV Diagrams for a Monatomic Gas?

I’m having trouble with a Thermodynamics Assignment and could use some help. I’ve been given the below graph and told to consider the processes shown for a monatomic gas. I’ve been asked to answer these questions with no further information besides the graph.
2. ### LaTeX Do Latex diagrams work in the preview mode?

I pasted examples (taken from old threads) of doing commutative diagrams in LaTex into the message editor and tried them in the preview mode. They didn't display. Should a correct example work in the preview mode? I'll paste a couple in this message and see if they show up in the final post...
3. ### I Force Generated By Leg Muscles in Free Body Diagrams

Suppose a person is walking on the ground without slipping. For the free body diagram of just the person, only the frictional force is drawn in the horizontal direction. The force exerted by the leg muscles to generate a force against the ground is considered an internal force. What would be the...
4. ### I Can free body diagrams be used if friction at pivot is not negligible?

Are we allowed to use free body diagrams in dynamic systems where there is non-negligible friction in say the rotational pivot between two linkages? If so, how to incorporate friction into the equations of motion? If not, what method allows friction to be accounted for?
5. ### I Understanding diagrams of the late stages of stellar evolution

Hi, I have an upcoming exam in astrophysics. We have been told to make sure we study all figures and tables, s.t. we are able to explain them. However, I ran into these figures below, in my lecturer's PowerPoint and I do not know where they originate and aren't presented in my book. I'm having...
6. ### B Distance b/w 2 Points on Spacetime Diagrams: Meaning?

With one spatial dimension ## x ##, the spacetime interval between two events ## A ## and ## B ## is ## \Delta s= \sqrt{(ct_{B}-ct_{A})^{2}-(x_{B}-x_{A})^{2}} ## I have a technical question: on the plane of the graph (x,y=ct), the ordinary distance between 2 points ## A ## and ## B ## is ##...
7. ### Which Feynman diagram or diagrams include feasible processes?

Hello friends. I couldn't do it. Which Feynman diagram or diagrams has include feasible process?

9. ### I Feynman diagrams and sum over paths

Hi ! In a Feynman diagram, can we consider that the propagator specifying the transition amplitude of a particle (let's say, of a "real" electron, or of a "virtual" photon) between two points or two vertices, is in fact itself the sum of a multiplicity of probability amplitudes, each one...
10. ### LaTeX LaTeX formatting Feynman Diagrams incorrectly

I've been trying to get Feynman Diagrams to work in my LaTeX code, however, the output is not what it is supposed to be. I'm using TeXMaker and TikZ-Feynman to draw the diagrams. My code looks like this: \feynmandiagram [horizontal=a to b] { i1 -- [fermion] a -- [fermion] i2, a -- [photon] b...
11. ### I Trying to understand space-time diagrams

I need your help. I've just begun learning about space time diagrams. Below is my doubt:An event is shown as a point on a spacetime diagram Another frame has coordinates of space and time as: ##\begin{aligned} c t^{\prime} &=(\cosh \theta)(c t)-(\sinh \theta) x \\ x^{\prime} &=(-\sinh \theta)(c...
12. ### LaTeX Commutative function diagrams in LaTeX

I know that TikZ is probably the best way to do this but most Forums don't use it. I can make a rectangular diagram, but it's a bit clunky: Say I have the commutative function diagram: ##\begin{array}{ccccc} ~ & ~ & f & ~ & ~ \\ ~ & A & \longrightarrow & B & ~ \\ g & \downarrow & ~ &...
13. ### A PD code yields two different knot diagrams

The PD code [(2, 3, 1, 4), (4, 1, 3, 2)] seems to map to a non-unique knot diagram. I can describe the following two Hopf links with different orientations with this same PD code. As I understand it, while a link diagram does not have a unique PD code, a given PD code should map to just one knot...

Here is a simple scenario where Object A and Object B cross past each other on an x-axis (for simplicity sake, let's just assume that they somehow passed each other on one spatial dimension). As they cross past each other, a photon gets released in the positive direction, and then gets absorbed...
15. ### Parallel RLC Admittance, Current and Power Vector Diagrams

(An even longer-winded version was written and deleted out of mercy.) Assume an AC voltage at zero degrees applied to an ideal parallel RLC circuit. For a predominantly inductive circuit, the vector diagram for current should show the supply current in the fourth quadrant (i.e. with lagging...
16. ### Chemistry Using Pourbaix diagrams to calculate corrosion in water

Let us solve it for Cu at pH =8. I found this Pourbaix diagram. What is the electrochemical potential I should use to check that Cu is there the stabel form. Should I check for all values of E between the blue lines at pH = 8? How can I measure the E value in reality?
17. ### Drawing physics Diagrams with online software

Hello everyone, does anyone know any online websites/software to draw detailed physics diagrams, Like the ones we see in textbooks and research papers. I wanted to draw detailed ray diagram of a lens with mentioning all the angles and refracted rays which is supposed to depict a certain...
18. ### Relating k-values to energy diagrams and rate-determining steps

I'm trying to understand a little bit more about how k-values relate to rate-determining steps and energy diagrams. I always assumed that the lowest value of k (in the forward direction) was the RDS saw something in a handout that indicated otherwise. It explained that even though k1 > k2...
19. ### Inserting a subscript in the text in the following diagrams app.

I want to inset the following text ##f_{2,G_2}##, but it seems I cannot include a subscript to ##G## in the following app: https://app.diagrams.net am I missing something? can it be done? Thanks!
20. ### I Uncover Traps in Spacetime Diagrams: Bob & Alice's Cases

There are some traps for the unwary in spacetime diagrams. I'll note a few; does anyone have more? Let me use my favorite actors, Bob and Alice. Bob is the stationary observer; Alice is the moving one. Both are in inertial frames (or however one prefers to phrase it). We look at Alice's...
21. ### Force Diagrams for a Combined Mass

I know that the ##F_{AonB} = -F_{BonA}##, but I just wanted to check something. If object A is the truck, then the x-direction should have a vector coming from the force of the engine driving the truck forward, a vector pointing in the negative direction for friction, and a vector in the...
22. ### Solving Vector Diagrams: Finding Displacements & Velocities

Here is my attempt at the vector diagram: Could anyone give me any clues as to where to go from here? Is this diagram correct? I tried finding θ using inverse tan 50/15 but I don't think I can do that because that's mixing up velocity and displacement. EDIT: I copied and pasted the incorrect...

24. ### Feynman Diagrams, are these allowed?

These are my attempts, I have found two possibilities for each, but have no idea if they're 'legal'... Thanks in advance!
25. ### B Understanding Spacetime Diagrams | Basics Explained

Spacetime diagrams seem to be the most used explanation for relativity weirdness, so I’d like some clarification in how to make them, it anyone wants to help. (1) Light’s worldline is 45 degrees, obviously. No issues there, I don’t think. (2) How do I determine the angles of the moving frame...
26. ### I General relativity, Electromagnetism and Feynman Diagrams

We are discussing the introduction to Einstein field equation, so he start talk about the linearity in Newtonian gravity and the non linearity in GR. But there is somethings I am missing: > " (...) in GR the gravitational field couples to itself (...) A nice way to think about this is provided...
27. ### B Do any 3D Venn diagrams exist that have no 2D analogues?

If we were to use three-dimensional spheres to represent sets, could a 3D Venn diagram be constructed that could not be drawn as a normal 2D Venn diagram without changing the relationships between the sets?
28. ### Interpreting Energy diagrams for polyatomic molecules

Hello, I am trying to correctly interpret the energy diagram below. For example, a diatomic molecule can translate (kinetic energy), rotate (rotational energy), vibrate (vibrational energy). Each different type of energy is quantized and has associated modes (also called states). The...
29. ### I Causality for internel vertex in Feynaman diagrams

Eq 4.44 in Peskin and Schroeder. My question is: Does causality imply that time coordinates of z (internal vertex over which we doing the integration) should lie between the time coordinates of field phi(x) and phi(y)?
30. ### I What software can I use to make space-time diagrams?

In a few days, I will be hosting a Zoom-based meetup in which I will be explaining the Twin Paradox (time dilatation) and the Pole-in-a-Barn paradox (Lorentz contraction). To this end, I will need to make graphics of space-time diagrams like those in Wheeler's book Spacetime Physics. Can anyone...
31. ### Man on an Elevator -- Force Diagrams

I really need help figuring out where to start. I believe that every graph has a normal force pushing up on the person as well ag gravitational force pushing down on them. Where I am getting confused at is how the velocity plays into the scenario and if an acceleration of 9.8 m/s^2 downwards is...
32. ### Free body diagrams, coordinate systems origin/orientation

Hello, When solving statics or dynamics problems, one important step is to draw the free body diagram (FBD) with all the external forces acting ON the system. The "chosen" system may be composed of a single or multiple entities. The external forces have components that must be projects on the...

34. ### A What are some example Feynman diagrams in Yang-Mills theory?

Hi! So I have just been studying Yang-Mills theory advanced quantum field theory. In chapter 72 of Srednicki's book Quantum Field Theory they list the Feynman rules for non-abelian gauge theory. I was asked if I could show some sample allowed diagrams but I could not.. In standard particle...
35. ### Solving a Group theory problem using Cayley diagrams

hi guys i saw this problem : if G is a group and a,b belongs to G and O(a) = e , b.a =a.b^2 then find O(b) , but i want to tackle this problem using Cayley diagrams , so my attempt is as following : $$ba =ab^{2}$$ then i might assume b as flipping , a as rotation : $$fr = rf^{2}$$ then...
36. ### MHB Molecular orbital theory question about energy level diagrams

Hello, The sigma $(\sigma)$ molecular orbitals are symmetrical around the bond-axis while pi $(\pi)$ molecular orbitals are not symmetrical. For example, the linear combination of 1s orbitals centered on two nuclei produces two molecular orbitals which are symmetrical around the bond-axis. Such...
37. ### Sound Wave Interference and Finding the Path Differences with Diagrams

Question 1: a. λ=v/f λ= 340/85 λ=4 m b. Please see attached. Ihave tried to accurately and to scale construct a diagram representing the compressions and rarefactions of the sound waves. Since the wavelength of a wave is simply the length of one complete wave cycle, and I have found that the...
38. ### Books for the Mathematics of Feynman Diagrams

Summary:: What is (are) the best book(s) to understand the mathematics of Feynman diagram? Hello, Can anyone recommend some books for the mathematics of Feynman diagram? (I don't mind if they also include the physics; in fact it may be better). Ideally I would need books that are very...
39. ### LaTeX Drawing Lewis Diagrams & Chemical Equations with LaTeX

Hi, How to draw Lewis diagrams, Lewis symbols , chemical equations in LaTeX?
40. ### RLC-circuits where phasor diagrams don't work

When I studied Electronics I remember that there was some type of RLC-circuit where phasor diagrams could not be applied in order to find I, U and phi_u_i (φ_u_i). I've been searching the web to find that example. But I can't find it. Can anyone of you help me refresh my memory?
41. ### I Understanding Nuclear Fusion Cross Section Diagrams

I'm working on programming a particle simulation that visually shows the nuclear fusion reaction rate of deuterium at different densities and temperatures, but I'm having trouble understanding exactly how nuclear fusion cross section diagrams are supposed to be interpreted. (The simulation...
42. ### LaTeX Program or platform for figures and diagrams

When using latex for writing problems in physics, I find it difficult to make diagrams or figures (such as circuits, atwood machines, lenses, ...) so I wonder if anyone has some recommendations of programs or platforms that can make this "drawings" easy, possibly without the necessity of coding...
43. ### I Calculating 2nd Order Scattering Amplitude: Feynman Diagrams

In the following I will try to deduce the scattering amplitude for a specific interaction. My question is at the bottom, the entire rest is my reasoning to explain how I came to the results I present. My working Let's assume I would like to calculate the second order scattering amplitude in ##...
44. ### I Understand Spacetime Diagrams: Calculating Proper Time

I am trying to understand the basic conceptual ideas about the space-time diagrams. In spacetime diagrams we have events which are labeled as points on the diagram. Let us call we have an event on point ##A(0,0)##and another event on ##B(4,0)## measured by an inertial frame ##S##. This inertial...
45. ### I Interactive Spacetime Diagrams: Get Feedback on What I Built

I built the tool initially for myself to better understand how Lorentz Transforms and spacetime diagrams work. Then while trying to discuss it with a friend I need to put it online and it snowballed from there. Now I am wondering whether there is any value for others in what I have created...
46. ### Feynman Diagrams for Decay of Δ++ & Ξ- Particles

Δ ++ → p + π0 Ξ - → Λ0 + π-
47. ### A Looking Under the Hood of Feynman Diagrams

I'm currently working my way through Griffith's Elementary Particles text, and I'm looking to understand what's going on with the underlying Hilbert space of a system described using a Feynman diagram. I'm fairly well acquainted with non relativistic QM, but not much with QFT. In particular, I'd...
48. ### I Frank Wilczek on Virtual Particles and Summing diagrams....

Hi all, - an initial apology - there are a large number of threads on virtual particles on the site, and I apologize for adding another one. I had two questions - on a related note, the guidance provided by @A. Neumaier's FAW on virtual particles has been highly valuable for a novice . 1) Upon...
49. E

### B Probably a silly question about tree diagrams

Each node of a tree diagram corresponds to an event (i.e. a subset of the sample space), and the probability of the event at any node occurring equals the product of the probabilities along the path from the root to that node. So considering the following two tree diagrams, I would have...
50. ### A Questions about Dynkin diagrams

I have two questions: 1. It is said that just by using the Dynkin diagrams one can recover the entire algebra of the Lie group. But this is JUST the Algebra and not some representation, correct? 2. SL(n+1) and SU(n+1) have the same Dynkin diagrams, that also means have the same algebra?