Approach Definition and 565 Threads

Could I please ask for help regarding the last part of this question: At a given instant, a ship P revelling due east at a speed of 30km/h is 7km due north of a second ship Q which is traveling x degrees west of north at a speed of 14km/h, where tan(x)=3/4. Show that the speed of Q relative to...

Ok, so here is what I have so far: Suppose ##T_1## is infinite and ##\varphi : T_1 \rightarrow T_2## is a bijection. Reasoning: I'm thinking I would then show that there is a bijection, which would be a contradiction since an infinite set couldn't possibly have a one-to-one correspondence...

Hey everyone. I'd like to share some thoughts on a problem that I have because I think it would be interesting to hear how others peoples thoughts on the problem. I'm studying an intense physics/engineering program in terms of workload. Our main form of learning new material in school is...

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Could I please ask for help with the following question: A destroyer moving on a breaing of 30 degrees at 50km/h observes at noon a cuiser traveling due north at 20km/h. If the destroyer overtakes the cruiser one hour later find the distance and bearing of the cruiser from the destroyer at...

If we assume the energy of particles in an ideal gas follows a Boltzmann distribution, then the energy distribution function can be defined as below: , where k_B is the Boltzmann constant Since the energy of particles in an ideal gas are assumed to only consist of translational kinetic energy...

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Some sources state we seek 10 dof ( and so ofc this is a symmetric two index tensor.My question is why we seek 10 dof in the first place ?Many thanks

Well, I don't understand the integral part of ##1/(VD) = \int_0^{\hbar \omega_D}\frac{\tanh(\beta E/2}{E}dE## and ##\tanh(\beta E/2) \approx 1-2\exp(-\beta E)##, then he writes the following (which I don't understand how did he get it): $$\frac{1}{VD} = \sinh^{-1} (\hbar \omega/\Delta(0)) =...

I've found two methods for doing this problem and they give different answers. Method 1: Assume the larger nucleus does not move, and simply equate energies before the collision and at the point of closest approach:$$\frac{1}{2} m v^{2} = \frac{qQ}{4\pi\epsilon_{0}r}$$ Method 2: Assume the...

Summary: Questions about the Multiverse hypothesis and the 'No boundary' conditions approach in cosmology I have some questions about James Hartle and Stephen Hawking's 'No-boundary' proposal: - In their approach multiple histories would exist. These histories could yield universes with...

Hello, First post here. I have some data I am trying to do some forecasting on and was hoping somebody who knows what they're actually doing can verify what I have done. A few years ago, the company I work for developed a mobile app for its customers and about 1 year ago they added some new...

Here were my assumptions: Energy and angular momentum are both conserved because the only force acting here is a central force. The initial angular momentum of this particle is ##L = mv_0b## and we can treat E as a constant in the homework equation given above. I solved for the KE (1/2 mv^2) in...

In his well known paper “Information Theory and Statistical Mechanics” Jaynes attempted to formulated statistical mechanics as "nothing more" than the inference theory of many body mechanical systems. I am looking for critiques of this approach. Also of use would be summaries or reviews of the...

I'm looking for a book that describes the quantum field theory without going deeply in the theory with formulas or complex description of the mathematics under the theory. I know that this theory is really complex and it needs a deep knowledge of quantum physics in order to be understood. But...

mod note: positively no politics will be allowed Hello All: The current hot topic on the news is using nuclear weapons against hurricanes . But couldn't we use other approaches ,using some nuclear reactors mounted in a plane or balloon that emit calculated levels of radiation in the center of...

Consider a 3-body Newtonian system with equal masses such that velocity change at a given time epoch for a single body is given by: I am interpreting that if also change per epoch such that say which means as a component. So body state information propagates in a way that one could...

I was solving a question from an entrance exam that said the following: Consider 2 balloons very close to each other. A person blows air in the place at the middle of the 2 balloons. What happens with them? The answer is that they approach each other, but why? For me, the blow will increase the...

https://phys.org/news/2019-05-mathematicians-revive-abandoned-approach-riemann.html and more on the Reimann Hypothesis backstory from Numberphile:

Of course, there is probability theory in QFT. The partition function can be understood as a characteristic functional. What surprises me is there is little discussion about characteristic functionals, except for some 40 year old papers. It seems surprising to me that physicists, being used to...

Hello. I have three questions about a claim made by Stephen Hawking in his book, 'My Brief History' and I would be grateful to receive some help concerning it please. Here is a .pdf version of it...

I am following David Tong's notes on the Quantum Hall Effect (https://arxiv.org/abs/1606.06687). One of the approaches he takes to the FQHE is the composite fermion approach (Section 3.3.2). There are two things I am struggling with. First of all he says that a vortex is something around which...

I know that in some Bohmian papers (like https://arxiv.org/pdf/quant-ph/0303156.pdf), electron-positron pair creation and annihilation is modeled by different methods like stochastic jumps in the configuration space. My question is, is there any Bohmian approach to reproduce all of the...

I'm having trouble understanding a specific line in my lecturers notes about the path integral approach to deriving the Klein Gordon propagator. I've attached the notes as an image to this post. In particular my main issue comes with (6.9). I can see that at some point he integrates over x to...

Hello, My understanding of the scientific approach when faced with an unknown sequence: Hypothesis: There is an order/signal/bias/code = Goal to achieve Null hypothesis: Absence of bias/order/code = Equal Probability = Target to destroy. Science tries to break the code. In order to prove the...

There's an MIT lecture on youtube where they talk about novel high temperature super conductors and how it will vastly benefit fusion. He claims that these higher temperature super conductors can generate a stronger magnetic field with just liquid nitrogen. They also claim that keeping the...

Hi. An ant walks with 1 cm/s along a rubber rope with initial length 10 cm that is stretched uniformly with 10 cm/s. Find its velocity at time ##t##. This is a a well-known problem, but I'd like to know what's wrong with the following alternative approach: At time ##t>0##, any point ##x_0## on...

Homework Statement Two objects ##1## and ##2## move at constant speeds ##v_1## and ##v_2## along of two mutually perpendicular lines. At the moment ##t = 0## the particles are located at distances ##l_1## and ##l_2## from the point of intersection of the lines. At what time will the two objects...

Hi, This is not homework. I am struggling with a puzzle from this book (page 6, puzzle #13). I know the answer of the puzzle but I can't seem to figure out a good approach. 1. Homework Statement A man left legacies to his three sons and to a hospital, amounting in all to $1,320.00. If he had...

Consider a massless string which can rotate about a fixed pulley (first picture). The coefficient of static friction is μ. Assuming that the motion is impending, the goal is to find the equation that describes the variation in tension of the string. ( T2/T1 = eμΦ where Φ is the subtended angle.)...

Homework Statement 180kmol/hr of a three component mixture made up of 60 mol % A, 25 mol % B and 15 mol %. Component A is the most volatile ,component C is the least volatile. The mixture is to be passed through a 2 stage distillation process. 80% of component C leaves the bottom of the first...

https://phys.org/news/2019-01-scientists-stabilizes-fusion-plasmas.html By applying more RF power to the unstable 'bubbles' that form in the plasmas.

Homework Statement A dilute gas consisting of N hydrogen atoms in equilibrium at temperature T and pressure P. A fraction of the atoms combine to form diatomic hydrogen. For ##N_{s}## single atoms and ##N_{d}## diatomic molecules, the free energy of the system is $$G =...

Previously I posted a problem concerning Electron-neutrino scattering, but as I couldn't describe the problem clearly, so I am trying to post the problem using latex codes to present it in the correct way. For a couple of months, I am trying to calculate the invariant amplitude of the Neutrino...

For a couple of months, I am trying to calculate the invariant amplitude of the Neutrino electron scattering in the standard model (SM) approach where I am not considering any kind of approximation and using the SM propagator for W Boson and Z Boson. I tried to do as following, find out the...

In Summary: I have a test Friday in modeling mass-spring-pulley systems, and I'm struggling to tie everything together. We're using the textbook System Dynamics 3rd Edition by William Palm III, and while it does a great job describing the individual components of each system, it does a crappy...

Two pontoon boat design approach and how to find center of gravity, center of buoyancy, buoyancy, volume of displacement, meta center, meta centric height. I need to know is there a different approach to designing dual hulled boat than a single hulled boat and all the formulas and examples I...

This is not really a homework problem. This is something I enjoy thinking about. 1. Homework Statement How many people should there be in a group to have a 50% chance of at least two of them having the same birthday. I know that there a many pages explaining how to solve this and the answer...

Work in quantum foundations is partly considered important because of the hope that the way we think about QM may point to a road to quantum gravity. Lucien Hardy, who is well-known in quantum foundations for his reformulation of QM in terms of five "reasonable" axioms, is one of the people who...

I am currently an "intern" at a company for a position primarily involving drafting cell site equipment. That is going quite well. But the owner of the company (an old friend of mine) has asked me to look up computational fluid dynamics softwares and begin to tinker with one, because he is...

Finding the Nearest Neighbor in a dataset has always been considered difficult, needing data-specific coding. Now some researchers, trying to prove there is no universal approach, say they have found one. This first link is to the 'popular' article...

Hi. I'm trying to get an idea how to look at the beginning, before the cosmic background radiation (CBR) and what we can detect with our eyes, and what we can assume about earlier times than light was around. I was looking into the red shift effect effect, as not only a measure of relative...

I am currently taking my first Quantum Mechanics course and was given this problem in a practice set(we are supposed to refer to old intro textbooks). We haven't covered the photoelectric effect (just theory) much in class and reading through other textbooks, I wasn't able to find any similar...

I currently have a job as a University Helpdesk / Jr. Network Engineer and it is very chill at 29 hours a week. I have been in university for over 5 years now (switched major from IT to computer engineering) and I want to get my degree finished. I have saved up enough money to go to school...

Hello folks, got a question regarding cooling tower I will like to understand. I got some performance data from some cooling tower makers on the condition of how the cooling tower will operate at different wet bulb temperature. Assumeing flow and fan power is constant, what i observe was the...

Homework Statement Charged sphere with a mass of 15 mg and charge 2 nC moves with a speed of 15 cm/s towards a fixed point charge of 3 nC. How close will sphere approach charge? Homework Equations K=(1/2)*mv2 U=k*(Q1Q2/r) The Attempt at a Solution So I am not sure I approached correctly but...

hi, i don't know if this qualifies as a question or not, but this is something i can't really understand. i am an engineering undergrad, when we are learning about the pros and cons of different method of doing anything , for example maximum power point tracking in PV systems, we discussed a...

Homework Statement Homework Equations J = nqvd J = I/A Q = It The Attempt at a Solution Basically we check whether the variable that we are looking at is proportional or inversely proportional. However, at what part do we stop? Where is it okay to substitute say Q = It and where is it not...

Homework Statement It's not a piece of homework, I'm doing a project and I've been wondering how I may be able to show it mathematically. I've covered the material before but it was a long long time ago... Homework EquationsThe Attempt at a Solution [/B] A-Thinking about modelling my "ship"...

Hello PF, I’m going through a book called “A First Course in the Calculus of Variations.” I can’t remember who the author is at the moment, I’ll post it later. Anyway, I’m having trouble with one part: suppose we have a function ##y (x)## that gives a continuous polygonal curve from ##x = a## to...