Explanation Definition and 982 Threads

I want to know how the Jiskoot sampler work but the manual is too brief and complicated, can anyone explain how it work in a simpler way with little bit of picture? I really appreciate it! (You can easily find the manual by searching: Jiskoot 210 sampler)

I have read about how magnetism arises from electric interactions and relativity. But in that respect i don't see how perpendicular wires can exert magnetic forces on each other. The movement of the charges is perpendicular so length contraction does not occurr in the direction of the current...

I'm not sure what Gauss's law really means. "The electric flux through any closed surface is proportional to the enclosed electric charge." How does this apply to finding the electric field? apcentral.collegeboard. com/apc/public/repository/ap11_frq_physics_cem.pdf Look at parts 1 a and b. Part...

Hello everyone, Finally I found a useful website where I can find the answers of my questions:) I will take signal processing course soon and I thought "building a low power fm transmitter" is a bright idea to train myself to a certain level... Though I need your help and I don't have...

explanation for "Incompatibility with special relativity and momentum conservation"? Can anyone provide an explanation for this claimed contradiction between basic electromagnetism and momentum conservation? (Sorry, as a new member I can't post links.) News article: "Textbook...

A falling object with no initial velocity with mass m is influenced by a gravitational force g and the air resistance which is proportional to the object´s speed. By Newton´s laws this can be written as: (1) mg-kv=ma or (2) mg-kv^2=ma (for large velocities). I assume that k is a...

Hi guys, I read about inertia on various websites and my textbook but I don't quite understand it. I just don't get the general understanding of it. I read that mass is the only variable, however since F=ma, and a=0 so won't there be no variables? My teacher gave us this question: you push an...

Hi, Could someone please explain what happens when an ice cube is put into a glass of hot water? I'm talking about the phase change and how the water gets cold. Thanks!

Homework Statement I have a bit of a problem in class. I am attempting to do an assignment on sound in relation to a guitar. For this I need to explain how the guitar is a highly energetic intrument. I do not know if looking at is like a helmholtz resonator is a waste of my time or not but I'm...

Explanation on how these solutions can be "easily" seen Homework Statement Show that x1(t)=cos(t) and x2(t)=sin(t) are both solutions to the following Equation. Homework Equations (d2x/dt2) + x = 0 The Attempt at a Solution Ok, So I just cannot understand how this can easily...

I have attached a file with my question. From what i see the flux for both surfaces will be 0. I am unsure and need a little of explaining

Could the cosmological redshift be explained also as a change of the fundamental physical constants with distance? Say Planck's constant changing over billions of light years, instead of interpreting it as a Doppler effect due to a recession speed? Yes, I know, Occam's razor would favor the...

I took a physics competition recently and found I missed 6 questions on electromagnetic induction and the like. I've always been shaky here, so I'm wondering if anyone can give me an online resource, or just explain to me exactly how it works (i.e., Lenz's law, etc., etc.)? I'm sorry for not...

Exactly what the title says. The prompt is this: Chose an actual example of scientific explanation, and use it to evaluate Hempel's and Ruben's accounts of explanation. I am not understanding the second part, how I am supposed to use an example to evaluate Hempel's and Ruben's accounts of...

we have just started to learn a new chapter in my physics class about de broglies hypothesis. In my textbook it shows a diagram of a line of electrons being fired at a constant speed, hitting a sheet of thin metal foil and then diffracting. The explanation in my book says ' A narrow beam of...

I don't have the intuitive picture of thermodynamic 2nd law, in terms of statistical mechanics. That is, why should the number of microstates be maximized in equilibrium? Anyone gives an intuitive explanation? Thanks a lot.

Explanation for Rayleigh Criterion?? I just want to ask what is the reason behind Rayleigh criterion which states that items are just resolved when the maxima of a diffraction pattern coincides with the first minima of the other diffraction pattern. I have tried finding the answer but to no...

Hello all! (I'm new to the forum) I'd like to ask if you could give me a simple explanation regarding the 6j symbols: I don't understand their formulation in terms of Clebsch-Gordan coefficients with three angular momenta and the related "tetrahedron rule". Alternatively, could you please...

What makes the motion start? What makes it stop? Does the ride move down? What force causes this motion? Does friction affect the ride? Where and how does the ride accelerate?

http://asymmetricphotons.davehewitt.com/__oneclick_uploads/2012/03/asymm.JPG While playing with lasers in a simple home setup, I have produced asymmetrical diffraction patterns and have been unable to locate explanations in the public domain. By using a green led laser and two parallel panels...

Hi, with the ideal gas law we have: cp = CV + (∂V/∂T) * P = CV + Nk (constant P) can someone explain why it intuitively most be so that, the heat capacity at constant pressure is independent of pressure? I mean surely a gas at high pressure wants to expand more?

Hi. I was just reading the explanation of superfluidity in He-4 (from the beginning of QFT Methods in Statistical Physics by Abrikosov et. al.). There is something I don't understand. At finite temperatures there is a "gas of excitations", which they take to be moving at an average velocity v...

Hi, there's this simultaneous equation problem, however I already know the solution, I just want to know more about the solution. a+b+c=2,bc+ac+ab=-5, abc=-6 The solution is: Consider the polynomial (x-a)(x-b)(x-c), where a,b,c are constants. (x-a)(x-b)(x-c) = x^3-(a+b+c)x^2+(bc+ac+ab)x-abc...

I suppose if you try to explain the existing theory, with a thought, this is not against the forum rules.. So far as I know is our clock based on the rotation of the earth. So our time has defined in that way. Everywhere on Earth is our clock running in the same rate. Suppose...

I want to understand the behavior of heavy electrons. For example is the mass actually changing? If so it would imply that a gravitational field could be affected by an electrical field. I am looking for good understandable references.

It is claimed that DCQE is equivalent to a single-photon double-slit setup. However, In this experiment, the 351.1nm Argon ion pump laser beam is divided by a double-slit, which means the actual photon rate is 1013 times higher than in a single-photon setup. Consequently, it makes it possible...

This article appeared March 2nd on Science Daily. Quite interesting. Any comments? http://www.sciencedaily.com/releases/2012/03/120302101413.htm

from my thinking nonlocality and entanglement are never a problem because in a totally determinstic universe, the information about what is going to be instantaneously tranferred from a to b is already known to the universe. we may not be in block time but the universe acts as if it were. this...

In this link (https://www.physicsforums.com/showthread.php?t=523874 ) there's an example of proof by induction. Somewhere in the explanation there's the phrase: Why they decided to multiply both sides by x+1?

Hello Forum, we all know about the experiment of the spinning bucket full of water. The water does not fall if the speed of the bucket is right (at least equal to the critical speed or larger than it). If there was no bucket the water would not fall on our heads either if the water moved...

Hello, First of all, please excuse me if I posted in the inappropriate place.. While a student few years ago, I used to work a lot with advanced differential geometry concepts, but never got an intuitive view of HOW humanity got to think about parallel transport, why it contained two words...

Why the voltage drop across the insulator is linear in the band diagram of a MOSFET??

I have now finished my lectures on classical mechanics, but I'm a bit ashamed to say that I still don't understand the concept of torque fully. Let's imagine this. We have a rod being acted on by the equal and opposite forces, but in different distances from the centre of rotation (attached...

In 2-5, an analogy is given for electromagnetic field: two corks in water, and the effect of jiggling one cork on the other (probably the up and down motion). Now, that sounded more like water is a medium propagating the energy. But the electromagnetic waves require no medium for propagation...

Homework Statement 200g weight spring unstretched length: 0.238m spring stretched( 200g hanging on spring): 0.305m Problem: Need to find length of a cord long enough so that the 200g weight can have the best bungee jump ever (barely not touching the floor which is 10m high) Homework...

Okay, so hi. I am brand new here at PF and I am signed up to ask this because this site appears to have allot of people who actually care and explain how to answer things. I have a spring and a 200g weight. - The unstretched spring is: 0.238m long - Stretched spring (with 200g weight...

Hello, Looking through a book on calculus I found the following explanation for the chain rule and I have one unclear thing that I'd like to ask for help on. The canonical example is used, y is a function of u: y = u^{n} and u is a function of x (let's say) u = 3x - 2 therefore by composition...

Homework Statement My Textbook gives the following example problem: Cournot Duopoly with incomplete information. The profit functions are given by: u_i = q_i(θ_¡ - q_i - q_j) Firm 1 has one type θ_1 = 1, but firm 2 has private information about its type θ_2. Firm 1 believes that...

This might sound like a ridiculous question, but could someone please give an intuitive explanation of what a statistical model is? I have always thought that it was just a tool used to make inferences about data, but I was told very recently that this definition is not entirely correct. Could...

I'm trying to work out the proof of combinations with replacement, but I can't quite understand the result of it. (n+k-1)ℂ(k) is the result, could somebody please explain this to me?

Any help on this random question would be greatly appreciated. The acceleration vector is *defined* as the change in the velocity vector given a change in time, and the magnitude of the acceleration vector is in d/s^2. According to the laws of physics, acceleration in a given direction is...

Here is an article that shows that taylor series for sinus becomes very accurate: http://dotancohen.com/eng/taylor-sine.php I wondered if I could prove the sinus values. Explanation for taylor formula have I found here before but the proof for derivative of sinus and cosine relies on values for...

I recently came across an odd phenomenon known as Mpemba effect. It says that hot water freezes quicker than cool water provided that temperature difference is not too much. E.g. it can be, say, 30 degrees Celsius and 50 degrees Celsius but not something like 99 and 1. Unfortunately, the book...

Can anyone explain to me what the phase constant (phi) is regarding the equation for displacement in simple harmonic motion and tell me if there is any equation to get it because I have looked at some answers to simple questions and in the answers they have just neglected the phase constant...

how is mimicry not a "just-so" explanation for similarities b/w species? ok obviously its not but this is what it seems like to me..cant wrap my head around this for some reason, please explain: I am drawing a distinction between behavioral and appearance mimicry.. So how is mimicry (in...

I'm having some troubles understanding the concepts of quotient algebra. May someone explain me what exactly they are, giving some concrete examples? I know that a quotient set is the set of all equivalence classes, but it sounds very vague for me and i can't make the analogy with quotient...

We just did atomic physics in class, and my teacher assumed everyone had already taken chemistry so she really skimmed through the material, and I have yet to take chemistry so I am beyond lost with this chapter. I read the chapter and it is so technically written that I don't comprehend it...

I wasn't sure where to put this post, but I'm interested in the Kardashev Scale and what the different Types of Civilization are in relation to us. I'm only somewhat familiar with Types 1-3 but am interested if it can go higher than that and how it can be described.

http://xanadu.math.utah.edu/java/brownianmotion/1/ I can't imagine