Path Definition and 1000 Threads

I am a freshman at a UC currently majoring in Evolutionary Biology and Chinese, however, I will be dropping the biology in favor of enology when I finish the required classes. This is not much of a change in interest for me as Enology is essentially biochemistry and microbiology. Although I am...

Homework Statement A model car of mass m moves on a horizontal track so that its displacement r from a fixed origin at time t is given by r(t)=2cos(t)i + sin(2t)/sqrt2j where 0<t<2pi (a) If r is the position vector of a particle, explain the physical significance of r . r and show...

Homework Statement A model rocket is launched straight upward with an initial speed of 50.0 m/s. It accelerates with a constant upward acceleration of 2.00 m/s^2 until its engines stop at an altitude of 150 m. How long after lift off does the rocket reach the maximum height? from...

Hi everyone. I know there are some medical dosimetrists and physicists in this forum who have provided useful advice. I still have some questions, if you don't mind. Basically, my background consists of a B.S. and M.Sc in physics with not so stellar grades (~3.0 GPA). I graduated almost 7...

Hello assume I sample signal between Transmiter to Reciver T->R Is the chanell respone would be the same to R->T also? especially I wonder about knife difraction effect ( Fresnel zone )

I'm in my junior year of college of a major in physics, and I'm already considering my job oportunities. In a country like mine (i live in Colombia, by the way) is kind of hard to get a job as a researcher if you don't want to be a professor (my case) and the global landscape doesn't seem very...

In that point in life where I have to make the hard decisions for my future and was just wondering what kind of university path you have to take to get into medical physics. Do you need an MD, PHD? Should your undergrad be in engineering? When do you specifically specialize into medical...

Hi: I am 36 years old. I like very much artificial intelligence and in particular speech recognition. However, I would like to study a career in telematics and after that a master in artificial intelligence. The reason for my first election is that there are some subjects like signal...

Hello everyone. I understand how to figure out the paths of the free particles following the principle of extremal proper time, but... where does it come from? I mean, how it's derived that particles follow a path of extremal proper time in space-time? I know that for example in flat space-time...

Hi everyone, I am having trouble finding the answer to a homework problem. I don't seem to understand what the question is exactly asking for. The problem is: find the path of a particle with an initial position 10er + 1.0eϴ and an initial velocity 0.1er + 0.8eϴ

My main passions involve anything having to deal with audio synthesis and manipulation. I love sounds (not even necessarily musical) and love even more the topics of electronic and computer generated sounds. I am mainly interested in computer-related audio processing and generation. I would love...

Hi all, I am trying to follow the derivation by Carroll of the parallel propagator in http://preposterousuniverse.com/grnotes/grnotes-three.pdf notes, beginning page 66 or so. My question is with the integral in equation 3.40. 1) why is it that this is an integral over a simplice, and...

Homework Statement Let \vec{F}: ℝ^{2}->ℝ^{2} be a continuous vector field in which, for every (x, y), \vec{F}(x, y) is parallel to x\vec{i}+y\vec{j}. Evaluate \int_{γ}\vec{F}\cdot d\vec{r} where γ:[a, b]->ℝ^{2} is a curve of class C^{1}, and it's imagem is contained in the circunference...

If $${C}$$ is the straight line that connects points in the plane $${(x_i, y_i)}$$ and $${(x_f, y_f)}$$, find a path $${\tmmathbf{r} (t)}$$ that traces out $${C}$$ starting at the initial point $${(x_i, y_i)}$$ and ending at $${(x_f, y_f)}$$ as $${t}$$ goes from zero to 1. Now the path that...

I've been studying the path integral approach to QM on my own, and trying to draw some analogies between the partition function of QM \begin{equation}Z_{QM}=\int D\varphi e^{\frac{i}{\hbar}S[\phi]}\end{equation} and that of statistical mechanics...

Homework Statement A particle moves along a circular path of radius 6 m, with constant linear acceleration of 1 m/s/s. Determine its total acceleration after 2 seconds. Homework Equations Can't find any. That's why I'm here. The Attempt at a Solution I assume there's some...

How many different ways can I get to the square marked with X if I can't go through the black spaces? http://i.imgur.com/HCSoD.png This is the original image. Essentially, how can I get to X abiding by checker rules (a piece can only move diagonally forwards by one square at a time by only...

Hello all, I have a fundamental question regarding batteries/power supplies that I've been wrestling in my hand. Essentially, what I'm stuck on is this- Why can't you create a simple circuit going from the + terminal of a power supply, through a lightbulb, and straight to ground (Earth)...

Hi there, My teacher gave me a homework, but this Theory of Plasticity is new and difficult to me. He has calculated the strain according to path (1), now I have to do with the path (2) and (3). This is what he did with path (1): ε11=∫(1/E)dσ11 +...

Homework Statement When light reflects from a thin film back toward the source, what is the path length difference? The Attempt at a Solution A. It is equal to twice the thickness of the film. B. It is equal to the thickness of the film. C. It is equal to half the thickness of the...

Hello World! I want to know if it's posible to do (this combo): BSc. Ecology & Environment (just enough biology, chemistry, physics, geology..) MSc. Integrated approach to Natural Sciences (same aswell) Phd in Biology or Physics? for example after the masters degree I might focus on botany...

Hey all, I am looking for some advice on what my options are to change career path. I will graduate this summer with a degree in Electronics and Electrical Engineering and have already secured a graduate job within a very reputable power engineering company. The job is everything I could have...

Homework Statement http://img534.imageshack.us/img534/6164/questionv.jpg Homework Equations ω = dθ/dt v = dS/dt The Attempt at a Solution I used the second expression for the tangential speed: v = \frac{dS}{dt} = r \frac{d \dot{\theta}}{d t} = (b-ct) \frac{d(kt)}{dt} \therefore \ v(t)...

Homework Statement Two in-phase speakers 4.50 m apart in a plane are emitting 1690 Hz sound waves into a room where the speed of sound is 343 m/s. Consider a point that is 8.50 m in front of one of the speakers, perpendicular to the plane of the speakers. What is the path difference (in...

I am reading a paper from Yakir Aharonov and others revisiting Hardy's paradox and I have a question. Let me state the notation first as brief as possible so that we can use it in the discussion: * a positron e+ goes through either the overlapping arm o+ or the non overlapping arm no+ of a...

Homework Statement The more I think about path difference, the more confused I get. First of all, HOW DO PEOPLE know that the path difference is dsinθ? Why do we draw a line coming from the first ray that is PERPENDICULAR to the second ray when determining path difference? Please see...

It is my understanding that some engineers working in aerospace find that a role in management best suits them and seek to climb the ladder of the company they are working for, where as others focus entirely on the technical, R&D side of things, content to stay in the same position indefinitely...

Hi, I am a sophomore in college and I'm a Computer Science major, but I'm terrible in math. It seems like no matter how long I spend on my work, I don't get it. I'm actually supposed to be a junior, but I failed Trig last spring, then took a semester off, the the only class I could take was...

1. All in the picture 2.v2=u2+2as 3. I have no idea where to start, I went through all the equations but i don't have time or velocity to sub in :( It also has circular motion which may or may not introduce pi. I didn't think this would be relevant but anyway.

Let me just start by saying that engineering is a great field and I respect what engineers have done/are doing for society. Hopefully by the end of this (very long) post you will understand the position I am in and will be able to share your thoughts as to what I should do and what my options...

Due to various life circumstances, I've had to move around a bit for the past 8 years and haven't been able to attend the same university for long enough to earn a degree due to credits in residency requirements. I have earned 204 credits from a combination of: Harvard University, University of...

In a Mach–Zehnder interferometer experiment, can you measure which path the beam took by measuring the change in momentum of the (fully silvered) mirrors (i.e. if path A was taken then the mirror on path A was "pushed" a bit, if path B was taken then the mirror on path B was "pushed" a bit)?

Hi I am trying to design a three mirror off axis telescope. The free parameters are the offset between the apertures and distance betwen the surfaces. My question is for a system with 'n' elements/surfaces (n=3 in my case) is there a relation between optical path length and focal length of...

Problem statement attached. The correct way to do this seems to plug in your given x, y, z into F then integrate the dot product of F and <x',y',z'> dp from 0 to 1, however, this results in way too messy of an integral. Answer is 3/e...

Hi guys this is my first post since I've joined, so be nice! I've been playing around with a short lens spectrometer at uni, using a strontium-90 beta source. It basically consists of a long steel tube with the source housed at one end, and a solid state detector at the other, mid way there is...

Any advice? Situation is: Low undergraduate GPA (2.7) but top 4 percent scoring in GRE. Degree in Nuclear Engineering. No luck finding jobs in field. Back to school or other options? Help please and advice!

I have a BS in Mechanical Engineering and I've been out of school for almost 5 years. Several months back I started learning Java just for kicks, but I've reached a point where I'm pursuing more and more knowledge of CS concepts on my own, and the interested level is far exceeding that of...

If a car is going around a 360 degree circle at 1 g (its maximum centripetal acceleration, and its maximum total acceleration) and then longitudinally accelerates ("gives it the gas") at .5 g (or tries to, while still cornering) for the next 45 degrees, what would be the formula for the radius...

Homework Statement An object is constrained by a cord to move in a circular path of radius 0.5m on a horizontal frictionless surface. The cord will break if tension exceeds 16N. The maximum kinetic energy the object can have is:Homework Equations KE=1/2mv^2 U=mgh The Attempt at a Solution...

Homework Statement Consider the track shown in the figure. The section AB is one quadrant of a circle of radius 2.0 and is frictionless. B to C is a horizontal span 3.5 long with a coefficient of kinetic friction = 0.27. The section CD under the spring is frictionless. A block of mass 1.0...

Problem: My homework constantly refers to something called the optical path length, L - I'm not exactly sure what this is. It's in the equation below. This question is in relation to astrophysics and dust extinction in the Interstellar Medium. Relevant equations: Dust optical depth, τλ =...

If, at one particular spot a particle can from (point A), all the paths from that spot to point B cancel each other out, does that mean the particle cannot come from point A? Or likewise, if only some paths from point A to point B cancel out, and paths from point C to point B cancel the rest...

This question is about if I have a path dependent function but a definite path, then can I integrate along the path to form a 2 dimensional field and then take partial derivatives along directions other than the path? And e.g. are points along path A connected to path B? (Note: all paths start...

planet of mass m is moving in an elliptical orbit around the sun of mass M. maximum and minimum distance of the planet from the sun is r1 and r2. Find the angular momentum of planet about the sun.(Consider M to be fixed in it's position.) Angular momentum= m(R*v) At farthest point from sun...

I'm really getting frustrated right now, as I am unable to reproduce the two-point gauge-field correlation function (i.e. propagator) as derived from the path integral in an R_\xi gauge using operators from canonical quantization. I believe the polarization 4-vectors of the gauge field ought to...

Homework Statement Use the two path test to prove that the following limits do not exist.Homework Equations \lim_{(x,y)\rightarrow{(0,0)}}\frac{4xy}{3x^2+y^2} The Attempt at a Solution The book that I am using introduces the Two Path Test theoretically but does not show an example of how to do...

If an object is moving in a perfect circlular path, what function(s) describe its path as a function of time?

Homework Statement The problem asks: find the integral of gamma F.ds where F(x,y,z) = (e^z, e^y, x+y). gamma being a triangle with vertices: (1,0,0) (0,1,0) (0,0,1) going in a counterclockwise direction Homework Equations The Attempt at a Solution So I'm not even sure...

So I have been out of high school for 5 years and did not go to college after school because I ended up with a very good job in the trades area and did that up until now where I really started to realize that I must go back to school and follow something that I have an interest in. I was a B...

Homework Statement If all the heat transport is by phonons, estimate the mean free path of phonons in Germanium at 300K using the following data. Thermal conductivity=80W/K m; Debye temperature=380K; atomic weight=72.6; sound velocity=4500m/s; density=5500kg m^{-3} Homework Equations...