Path Definition and 1000 Threads

1. Ann's light clock uses a single photon that oscillates vertically between two mirrors separated by a distance d. She leaves the space station, accelerates to a constant .2c in a random direction labeled x. For her clock to continue working, the photon must move vertically as before, and...

Homework Statement Find $$\int_{C} z^3 ds $$ where C is the part of the curve $$ x^2+y^2+z^2=1,x+y=1$$ where$$ z ≥ 0 $$ then I let $$ x=t , y=1-t , z= \sqrt{2t-2t^2}$$ . Is it correct? Or there are some better idea? Homework Equations The Attempt at a Solution

Homework Statement Find the work done by the force field F on particle moving along path F(x,y) = -xi + 6yj, <I>C</I>: y = x^3 from (0,0) to (6,216) The Attempt at a Solution Drew the graph in the xy plane (y = x^3 is upper limit, x = 0 is lower limit) W = F ° r'(t) dt Vector field is...

Hi, I wanted to try to use cmd to compile and run a program in java. I have sucessfully compiled it. The compiler is working properly (C:\new> javac output the compilers functions), but I'm always getting the same error: "Error: Could not find or load main class hello". When I specify the...

Does gravity always move an object down the path with the steepest slope? I just finished reading about the vector gradient in calculus and a problem jumped in my head: "Can I make a formula for the work it takes to push an object from the bottom of a hemisphere to the top along the...

So I'm interested in doing research regarding a GUT after I graduate, but I don't know the best way to go about this. In regards to choosing my senior level courses, which courses should I be taking? Should I start thinking experimental or theoretical? I know this is a pretty wide subject...

Current follows the path of least resistance or shortest path. I just want to prove this or rather reproduce it using calculus of variations. I just want to show it in a fancy way. I want help to form the FUNCTIONAL for it. Useful equations: I=dq/dt=nqvA R=rho*l/A Where v is drift velocity...

Consider: \int d\phi e^{iS[\phi]}=\int d\phi' J e^{iS'[\phi']} where J is the Jacobian. If the transformation of variables to phi' is a symmetry of the action [i.e., S'=S], then this becomes: \int d\phi e^{iS[\phi]}=\int d\phi' J e^{iS[\phi']} But doesn't this imply that the Jacobian has...

Hi, It's great to find this forum. I'm teaching myself QM using Shankar, it's a great book, I've covered 8 chapters so far. My question is about the notion of using Path Integral method to calculate the propagator. The recipe given by Shankar says the propagator is U(x,t;x')=A\int...

Hello! I'm not sure if this was the right subforum to ask this question, but I figured I'd give it a shot anyway. Currently, I'm a student at a California CC looking to transfer to a CSU here. I'm majoring in physics and have knocked out all my lower division classes and will be...

I am in the process of choosing the topic for my thesis. Originally I came from a more theoretical branch of physics but I realized that I do not see my future in university research, but more in the industry. I want to do research with more direct applications, but now I am not sure what my...

Tricky Path Difference Problem in waves, help! (attachment) Homework Statement [SIZE="6"]check the attachment Homework Equations none needed for part (d) The Attempt at a Solution the first three questions of part (c) i got them out. answers were (c) (i) 2x10 ^8 ms–1...

I just found out for sure today that I have Asperger's Syndrome, and I'm wondering how this should inform which career path I should take. Here are the two paths I see in front of me: I can either study to become a theoretical physicist (something that's been a dream of mine for a long...

Hi all, Sorry if this is in the wrong place. I'm trying to understand probability theory a bit more rigorously and so am coming up against things like lebesgue integration and measure theory etc and have a couple of points I haven't quite got my head around. So starting from the basics...

In several places I've seen a derivation of the radius of a black hole by simply determining when the Newtonian escape velocity will reach c. Similar analogies are commonly used to explain light being bent by a gravitational field. So will treating light as a particle traveling at speed c in...

Hello, I have a general question regarding what is the best controller (PI, PD, etc.) to control the position of a mobile robot in order to follow a known path. The mobile robot at hand is a mechanism (a 4 bar linkage with its two base gliding on two parallel but not straight rails) and I...

Has path of a standing wave confined inside a metal box been measured and described? I'm thinking path is circular, or, oscillates/bounces back and forth like a pendulum. I'm thinking of a standing wave moving inside a metal rectangular box. Has the path of a standing wave inside a...

Homework Statement A lunar probe is given just escape speed at an altitude of .25 DU and flight path angle 30°. How long will it take the probe to get to the vicinity of the moon (r = 60 DU), disregarding the moon's gravity? Circular orbit, radius = 1.25 DU θ = 30° gravitational parameter =...

a pelican flying along a horizontal path... A pelican flying along a horizontal path drops a fish from a height of 5.4 m. The fish travels 8.0 m horizontally before it hits the watwe below. What was the pelican's initial speed? Well I'm guessing that y =-5.4m and x= 8.0 m...what do I...

Homework Statement A car is traveling eastward turns north by traveling in a circular path at uniform speed as shown in the picture. the length of arc ABC is 235m and the car completes the turn in 36.0s a) Find the acceleration vector of the car when it is at B. Express answer in terms of...

Hi, i know I've posted similar threads before but here it goes: im a second year university student studying biochemistry. Now in theory its ok, and some of the courses are fun but i have no passion for studying biochemistry. i thought organic chemistry would cheer me up but its pretty dull...

The attached file illustrate the method I didnt understand this actually from lecture,and i try to search inside books but also didnt find any thing. The notes are brief so u can't get complete understanding So anyone could help me find relevant resources or such one example only to get the...

Hello I have not familiarised myself with the mathematics etc I merely have the conceptual idea that, for example, with the two slit experiement and electron is permitted to take "all possible paths" from the electron gun to the detector screen. The thought occurred (and as will all thoughts...

Homework Statement There is a block suspended by a string with length 6m forming the radius of a circle. The block is 220kg and you are able to exert a 420N force in the x direction. How far from the vertical will the block travel. m=220kg r=6m F(x)=420 Find x(distance) Homework...

physcially, how electrons choose the path with min resistance if 2 paths of 2 differnet resistances electrons distributed & may if short circuit exist it take it how electrons know there is short circuit and how they know the path of min resistance ! Another question of a connection...

Simple question as described in the title: How did you know what path to choose when you were getting your PhD. Specifically, what made you think to yourself "This is the project I want to be apart of" when you finally made the decision to pick your dissertation/research topic. Tell me, I want...

Homework Statement I am given a set S consisting of the union of line segments from the point (0,1) to points (x,0) x-values are rationals from [0,1]. I want to show that this is path connected. Homework Equations Finding a continuous function f:[0,1] -> S such that f(0) = a and f(1) =...

Hello everyone, I'm facing a bit of confusion. I am currently in high school, taking a college level Calculus class and a college level Algrebra-Based Physics class. I am not sure whether it's because of the class, or if it's because of the math itself, but i seem to enjoy Calculus much more...

Homework Statement A record of travel along a straight path is as follows: 1. Start from rest with constant acceleration of 2.20 m/s2 for 15.0 s. 2. Maintain a constant velocity for the next 1.65 min. 3. Apply a constant negative acceleration of −9.92 m/s2 for 3.33 s. (a) What was the...

Hello everyone, Little back story, so when I began college as a freshman I thought I wanted to become a doctor. My sister already being in med school it seemed like a challenging and rewarding career which could ultimately make me a lot of money. However speaking with my physics teacher...

Homework Statement A tennis player slices the ball to spin and deviate from its normal parabolic path. What is an explanation for this phenomenon? I am having trouble visualizing the phenomena that is occurring with the slice and as well as the explanation give by the book. How is the...

Homework Statement This doesn't seem like much more than a kinematics problem but it's for an upper division mechanics course so I chose to post it here. Feel free to move to intro if necessary. Homework Equations kinematics equations The Attempt at a Solution I focused...

In May I graduated from a small liberal arts college with a Bachelors in Math (3.6/4) and in Economics (3.8/4). In July I shipped off to Vietnam where I am currently teaching HS Math at a large private school in Hanoi. I took a last minute GRE before I left and scored reasonably well IMO (V 159...

(It was hard to think of a title) This isn't really a question about a direct career path, so I hope it's the most correct place to put it. It's more of a poll of opinion about the school system, my life, and how I begin learning what I want to learn. So it's a career question in some sense...I...

Hello everyone, I have a question on applying to graduate school to study a different field than one studied for their undergrad degree. Specifically, I am due to graduate from a Boston area school with a combined electrical engineering / physics degree. I have an A/A- average, solid GRE...

Hello all, I will be learning about the path integral formulation, among other topics, in an advanced QM class during this upcoming semester, so I read ahead a little. I understand that, essentially, the propagator between two points in spacetime is the normalized sum of exp(i*2pi*S/h) over...

Hello all! I was recently watching a documentary which delved into the theory (is it a theory?) that quantum particles can be in two places at once; indeed, millions of places at once. I've heard this all before, but the one thing that I picked up on this time was that when a particle is...

Hello, I am a 14 year old about to become a freshmen and I already feel convinced I will become a physicist since I seem to have an good ability in the subject and I absolutely love science. I need some advice on how to start of high school on the right foot. I want to start getting a job...

Homework Statement Spring and Hanging Mass A block of mass 4 kg hangs vertically from a spring with constant k = 100 N/m which is attached to the ceiling and initially is not stretched or compressed. The block is initially held at rest by an external force. The block is then released and falls...

Page 35 Feynman Quantum Mechanics and Path Integrals (2-26)ψ=(iε)R I know it's a defination.But how to find some threads.How can we get this?

Hello all, A friend of mine has recently developed an interest (rather, an obsession) with the Calculus of Variations. He's familiar with linear algebra and also with the contents of Spivak's "Calculus on Manifolds", and is now looking for the shortest path to Gelfand and Fomin's "Calculus of...

Hi, I am wondering how i can calculate the classical mean free path of electrons in InSb given the following material parameters... zero field conductivity = 1.86e4 1/ohm m electron mobility = 45,500 cm^2/Vs Is it a case of working out the scattering time and multiplying it by the...

sorry if i posted this topic here..let P1 and P2 be a path partition of a graph.is it possible that P1 and P2 to have the same end vertices?

Hi, I'm planning to become an engineer and so far have narrowed my choices down to mechanical, electrical, or computer engineering. I do personal projects on my own time mostly involving circuits, but lately I have been troubled by the news of light replacing electricity in circuits(though I...

I don't know if I got this right, but as far as I know, if you are able to deduce through which slit the particle went through, it behaves classically, if you have no way of deducing through which slit the particle went through, it behaves in a quantum way (interference pattern). Now, I don't...

Schroeren's new paper "Decoherent histories of spin networks" made me aware of some work by two people at Cambridge DAMTP and London Imperial's Blackett Lab on the Quantum Zeno (QZ) effect in the path integral e.g. decoherent histories (DH) context. Schroeren's paper...

What kind of career path should i follow if i want a job whihc involves devising new and better ways of using computers and addressing particular challenges in areas such as robotics, physics and other sciences. I will start my undergradute course in CSE this year. After that what will i have...

Homework Statement Itzykson-Zuber ch. 9-1-1: If H=\frac{P^2}{2m}-QF(t) then \frac{\delta}{i\delta F(t)}\langle f\mid i\rangle_F=\langle f\mid Q(t)\mid i \rangle_F Ok, I understand that. But then it states: if H=\frac{P^2}{2m}+V(Q) then \int\mathcal{D}(q)\exp\left\{i\int...

I'm about to go into my final(3rd) year of a maths BSc in the UK at Warwick university, and am currently looking at what options I'd like to take given that I'm hoping to go down the path into theoretical physics academia. I currently hold offers for Imperial College's "Quantum Fields and...

In Feynman’s Path Integral formulation of QM, one starts by considering all possible paths between two fixed space-time events. Question: Must the wave-length associated with each allowable path divide evenly into the spatial length of the path?