Path Definition and 1000 Threads

I have a problem. Previously mcnpx ver 2.7 was working on my computer. But now I get an error like this. ''bad problem in xact in routine tpefil chg_mem error''. Can anyone help? Am I making a mistake in the installation? Is there something I'm missing when making the ''PATH'' and ''DATAPATH''?.7

How does the current flow in this circuit and what is its actual true path, regardless of any directions in the figure? What does the “5i” above the dependent source mean, and does the current flow according to the dependent source or the independent source? Are the two resistors 2 ohms and 6...

If a vector ##V(x)## being transported down a path ##l##, The vector field is described with equation: $$\partial_\mu V(x)=\Gamma_\mu V(x)$$ The solution of the equation can be described with parallel propagator ##P(x, x_0)##(in mathematics it is also called product integration): $$V(x)=P(x...

I recently came across the concept of 'mean free path', and some similar concepts in thermodynamics (the depth of my understanding is very shallow though, which is why I'm here). This is very much a shower though, so: Suppose I have a box filled with some some metal ball bearings, which I...

Refreshing... i'll start with part (a). Just sharing in case there is more insight... In my working i have, ##T = \dfrac{dr}{ds}=\dfrac{dx}{ds}i + \dfrac{dy}{ds}j + \dfrac{dz}{ds}k## and ##x=\tan^{-1} s, y = \dfrac{\sqrt2}{2} \ln (s^2+1), z=\tan^{-1} s## ##\dfrac{ds}{dx} = \sec^2 x = 1...

To boil down the question, if you have a body at rest and apply a constant force, it will accelerate and the work done on it will be F*s (or the integral version of that statement). However, as the body accelerates due to the force, does that mean, per a given time unit, more and more work will...

I get that if I put current directory in PATH like said above, I can execute commands from any directory. But what's the problem in that? How's other person able to come and execute it? Why does it makes system unsecure compared to the case where we don't put current directory to PATH? Can you...

The first step seems easy: computation of the $\theta$ and $\overline{\theta}$ integrals give $$Z[w] = \frac{1}{(2\pi)^{n/2}}\int d^n x \: \det(\partial_j w_i(x)) \exp{\left(-\frac{1}{2}w_i(x)w_i(x)\right)}.$$ From here, I tried using that $$\det(\partial_j w_i (x)) = \det\left(\partial_j w_i...

How did you find PF?: Google Search I'm new to this forum and I am currently 14 years old. I've recently taken an interest in physics(Due to popular science/ books and natural curiosity). But I have no idea what path to take so I could study it. I come from a poor and quite unsupportive family...

Good morning , I managed to simplify the physics of my car with only the centrifugal and traction forces. If I'm in control of it, the realism is acceptable for a city builder. On the other hand, I encounter a problem when the car follows an array of points. The path of the car on my graph...

I'm posting this in "Quantum Physics" although it is just as much "General Relativity". A paper entitled "Quantum gravitational corrections to particle creation by black holes" was published in Science Direct earlier this month. It appears to provide an event horizon mechanism for holding...

For part(a) of this problem, The solution is, a. 160 J In part (a), are they referring to the simi-circular path from R to S instead of the path from R back to R? I though the closed path would be the path from R to R, or the path from S to S, where both give W = 0 since ##W = P(V_f - V_i) =...

For this I am trying to prove that angle theta between PQ and QO is equal to theta highlighted so that I know I can use theta is the path difference formula. I assume that the rays ##r_1## and ##r_2## are parallel since ##L >> d## My proof gives that the two thetas are equal, however I am...

Objectives: - best path for optics needed to focus and "draw"/project a high resolution image onto a workspace around 500mm square (for a Laser Direct Imaging machine) - where to cost effectively purchase or make the optics necessary to build a prototype The problem: I need to project a high...

For part(d) of this problem, The solution is, However, how did they know that the object moves in a circle of radius 5.00m centered at (0,4.00m)? Many thanks!

Question: A ball is hit with a certain force and it starts with an initial velocity of V m/sec decelerating due to friction along a flat path and then up an inclined ramp coming to stop at the top of the ramp where the ramp becomes flat again (as per diagram A). The total distance traveled along...

If the distance between the centres of two molecules is σ, then imagining a a cylinder with radius σ the number of molecules can be given by πσ²cn where c = average velocity. So mean free path can be given by λ = c/πσ²cn = 1/nπσ². But do I derive it from exp(-x/λ)?

Reading the introduction to path integrals given in the latest edition of Zee's "Quantum field theory in a nutshell", I have found a remark which I don't really understand. The author is evaluating the free particle propagator ##K(q_f, t; q_i, 0)## $$\langle q_f\lvert e^{-iHt}\lvert q_i...

The object takes a step [x, y] in 2 dimensional space. This is represented the change in coordinate ##x \vec e_x + y \vec e_y## where ##e_x## and ##e_y## are basis vectors in this space. Suppose we define a non-linear / parametric transformation of this ##\vec e_x## and ##\vec e_y## basis...

The Delayed Choice Quantum Eraser (DCQE) experiment attempts to show that which-path information can be "erased," and interference recovered. I'll refrain from explaining the experiment, and assume you are familiar with the setup. I refer to the Wikipedia page about it, and the original Kim...

I expected this to be challenging but it's turning out to be much harder than I expected. I just flew back from Cuba to Toronto, got in at 315AM. It was a beautiful, clear and I had the window seat, so I took a bunch of pics. Now I'm plotting the flight path by analyzing the photos. It's super...

I understand that S (Ssys) is a state function but I can't understand why Ssurr and Suniv (or Stot) are a path function.

From plotting the given path I know that the path is a curve that extends from z = 1 to z=5 on the complex plane. My plan was to parametrize the distance from z = 1 to 5 as z = x, and create a closed contour that encloses z=0, where I could use Cauchy's Integral Formula, with f(z) being 1 / (z +...

Hello everyone, I am struggling to get insight into a certain set in 4D space. Given is a closed path in 4D-space with constant Euclidean norm $$\vec{\gamma} (\theta):[0,2\pi]\to\mathbb{R}^4, \ \ \vec{\gamma}(0)=\vec{\gamma}(2\pi), \ \ ||\vec{\gamma}(\theta)||_2 = \mathrm{const.}$$ I am looking...

I've found an interesting problem in an undergrad physics book which I've bought, and my high school teacher to whom I've showed it said it was intriguing, and didn't know the answer. A tube in the shape of a rectangle with rounded corners is placed in a vertical plane, and inclined towards the...

I'm a graduate theoretical physics student at the (almost) end of his master's degree with a fairly varied curriculum, as I attended both QFT (and sub-courses on qed qcd etc) and GR courses. However in my latest intro to quantum gravity classes I familiarised with tetrads and, after a lot of...

Does anyone have a clue what the gold points and associated lines represent? I notice that all the gold lines form closed loops (so they're not travel paths) and they cross themselves (so they're not contours). I can't think of any type of data that would result in this. I've tried to follow...

In the book it is mentioned that, in path c, the line integral would be: $$\int \vec{F}\cdot \vec{dr} = A \int_{1}^{0}xy dx = A\int_1^0 x dx = -\dfrac{A}{2}$$. but I think that dx is negative in that case, the result would be positive, right?

In Feynman’s path integrals, there is: ∫dq″Π0(t″,t′;q″,q′)=1 What is the funny pi looking symbol?

Fig.1 Fig 2 (the net of the cone) Point C is the turning point. ##\phi##= 90°. I wonder why the angle ACP is 90°. Is this a coincidence, or the "wire of minimum length" has anything to do with this? (Though, I thought the minimum length of the path can be acquired if ABP is a right angle)

This is the weighted, directed acyclic graph I created in JavaScript class WeightedDirectedGraph { constructor() { this.adjacencyList = {}; } addNode(node) { if(!this.adjacencyList[node]) { this.adjacencyList[node] = []; } } addEdge(node1, node2, direction, weight) {...

[Moderator's note: thread spun off from previous thread due to topic/level change.] This [Ed.: the claim that photons have a "path"] is a misconception of quantum theory already for massive particles. It's even more severely misleading for massless quanta of spin ##\geq 1##, which do not even...

Hi Pfq My question is about this experiment: https://www.nature.com/articles/s41598-020-68181-1 (the link was given by DrChinese. If all the impacts are conserved no interference can be seen on the screens. but if we only take the impacts (Y, yi) where Y is always at the same position on the...

Hi. I have this idea that might be useful for celestial navigation. If you were on a random place on the Earth, and you had a way of measuring the altitude of the sun above the horizon, at a precise moment, could you then predict the complete path, such that you could determine the altitude at...

I am aware that one usually starts from the Maxwell equations and then derives the masslessness of a photon. But can one do it the other way round? The action of photon would be ##S = \hbar \int \nu (1 - \dot{x}^2) \mbox{d}t##, where ##\nu## is the frequency acting as a Lagrange multiplier...

Hello all! I have been taking an academic break from school for certain mental health reasons that I won't waste your time talking about. Now, I am only a freshman in college. My school's physics department currently offers 2 majors: Physics and Physics/Astronomy. Obviously, I have lots of time...

I am 18 and currently in the middle of taking a gap year from high school to college. I am going to college this fall, and I want to go into college with a better grip on what I want to do than I have now. I absolutely love physics, science, and math. I also have a huge attachment to the idea of...

At the start of univerity I had a huge problem that really threw me off track. Thus during the first two years (4 year total due to masters) I focused my time on the core maths modules (maths 1, 2, 3, 4). In year 3 and 4 I sorted the problem and really got my head down and ended up achieving a...

Has any path/line/shape/contour function? And how find function of complex "path"? for example this?

Hi there, I've been stuck on this issue for two days. I'm hoping someone knowledgeable can explain. I'm working through the construction of the quantum path integral for the free electrodynamic theory. I've been following a text by Fujikawa ("Path Integrals and Quantum Anomalies") and also...

I am trying to understand the current path for corona. Assuming the corona appears on the high voltage electrode, how are the electrons actually flowing? I understand that with flashover a low resistance current path is created as the air is ionized but what is happening with corona?

I cannot seem to start answering the question as a result of the path not being provided. How do I solve this when the path is not provided? See picture below

Let's focus on obtaining how much will the ball deviate from a straight path and assume the spin of the ball to be ##11600## rpm and ##C_L = 0.4## to be the lift coefficient A pitcher is able to make a baseball follow a curved path by impinging spin on the ball (which triggers nonsymmetric...

In Richard Feynman's book "The Strange Theory of Light and Matter", in chapter 2, he explains how to calculate the probability that light from some source will be reflected by a mirror and be detected at some location. He explains how you sum up all of the probability amplitudes (represented...

lambda (rms)= v(rms) * t(rms) -- 1 Now I assume here that t(rms)=1/(√2*n*π*d^2*v(rms)) But this cancels the v(rms) term when used in eq (1) so the mean free path and the RMS free path would actually be the same (even later on when used in the aforementioned Survival Equation) I would like to...

My attempt: I think ##x## is the path difference so by using trigonometry, I got ##x=d \sin \theta## But my teacher said the answer is ##d \cos \theta## What is my mistake? Thanks Edit: Sorry, I found my mistake. My ##x## is not the path difference

We have the area of incandescence. Using that we can find the radius and subsequently the diameter. A=π* r^2 -----> r= 0.0025m so d=0.005m Using the formula (given by Clausius as we are not specified in question whether it's a Maxwellian distribution or not) Mean Free Path λ=...

While classical mechanics uses single action optimizing trajectory, QM can be formulated as Feynman ensemble of trajectories. As in derivation of Brownian motion, mathematically it is convenient to use nonphysical: nowhere differentiable trajectories - should it be so? Can this connection be...

Summary:: What is the best way to get into the Aerospace Engineering Industry? Hi everyone, I'm new to the physics forums. My name is Andrew, I'm going to be in my undergrad Senior year in mechanical engineering this coming fall. I've recently been looking into PhD programs and I've been...

Hi. I'm new and hoping for some discussion. I've been looking at some physics at home on my own while Covid-19 restrictions keep me off work. I'm not registered as a student anywhere and so don't have any chance to chat with other students or university staff. Hence, I'd be grateful for some...