Classical Definition and 1000 Threads

Homework Statement Let's assume that the classical ideas of space and time are correct, so that there could only be one frame, "ether", in which light traveled with same speed in all directions. Assume that the Earth's speed relative to the ether frame is our orbital speed around the sun...

Hello, I read the Feynman's QED book, where I learned that a photon has a intrinsic property called frequency. This property affect, for example, the interference profile when we have a lot of photon together. Ok. Now, thinking on an conventional antenna. When we have a 100kHz signal on...

Homework Statement A small sphere, with initial temperature ##T##, is immersed in an ideal Boltzmannian gas at temperature ##T_0##. Assuming that the molecules incident on the sphere are first absorbed and then re-emitted with the temperature of the sphere, determine the variation of the...

Homework Statement Greetings! I am reading section 2.8 of Jackson and trying to understand how completeness relation was derived. It starts with the orthonormality condition: ∫U_N ^*(ε) U(ε) dε =δ_{nm} We can represent a function as a sum of orthonormal functions if N is finite...

Hello everyone, I have to choose a book for classical mechanics. After reading a lot through the forum, I find that the book by A.P French and the one by Kleppner is a good buy for my undergraduate course in classical mechanics. Also, is the book by Mary Boas for Mathematical methods a good...

The relativistic mass-energy-momentum relation m^2=E^2-p^2 predates quantum mechanics by a couple of decades. It allows a particle such as an electron to have a negative mass-energy. If it's 1906, and you're shown this equation, do you have any way to show that the negative-energy solutions...

Homework Statement If A is a time dependent vector, calculate [itex] \int_{t1}^{t2} dtA(t) \times \frac{d^2A}{dt^2} [\itex] Homework Equations The Attempt at a Solution I think we should somehow relate it with something's derivative. \int_{t1}^{t2}A(t)\frac{d^2A(t)}{dt^2}dt=...

I am working through Leonard Susskinds 'the theoretical minimum' and one of the exercises is to show that H=ω/2(p^2+q^2). The given equations are H=1/2mq(dot)^2 + k/2q^2, mq(dot)=p and ω^2=k/m. q is a generalisation of the space variable x, and (dot) is the time derivative if this helps...

Hi all, So basically I would like to know if it's possible. I'm a first year undergrad and I did classical mechanics first semester but I didn't do that well in it. So I'm not sure if I need to use my holidays to catch up with it before we do Electromagnetism during second semester. I would...

Homework Statement Suppose you want to make a velocity selector that allows undeflected passage for electrons whose kinetic energy is ##5x10^4eV##. The electric field available to you ##2x10^5V/m##. What magnetic field will be needed?Homework Equations ##u=\frac{E}{B}## u is velocity, E is the...

I have taken a look at Kleppner and Kolenkow and that seems around the right level of difficulty but I was wondering if there were any other books that worked well alongside the Walter Lewin lectures on OCW. Would K&K? Also, where does K&K go up to? Does it include all undergraduate...

I have been working through the IIT Madras Lecture Series on Classical Mechanics on Youtube. They are excellent so far but I was wondering if anyone could point me towards either some problems designed for the course specifically or some other problems that work well with it. I would like to...

I'm studying classical mechanics and I'm stumbling in the quantity of differential identities. Being S the action, H the hamiltonian, L the lagrangian, T the kinetic energy and V the potential energy, following the relationships: But, the big question is: that's all? Or has exist more...

In classical electromagnetism, Coulomb's constant is derived from Gauss's law. The result is: ke = 1/4πε = μc^2/4π = 8987551787.3681764 N·m2/C2 Where ε is the electric permittivity of free space, μ is the magnetic permeability of free space, c is the speed of light in a vaccuum, and 4π is...

Hello everyone! I was reading the following review: http://relativity.livingreviews.org/open?pubNo=lrr-2009-4&page=articlesu23.html And I got stuck at the first equation; (10.1) So how I understand this is that there are two variations, \tilde{q}(t)=q(t)+\delta q(t)...

Homework Statement Two cylinders, that can rotate around their vertical axis, are connected with a spring as shown in the picture. Moment of inertia ##J## is the same for both and they also have the same radius ##R##. Distance between the axes is ##L##. Spring with constant ##k## is ##d## long...

I'm thinking about being a physics major with a double major in Earth Science. At my college Classical Mechanics is a required course for a physics major, whereas General Physics is required for the Earth Science major. There is an option at my school to take General Physics instead of Classical...

I currently have Classical Mechanics by Douglas Gregory. I found that there are a lot of errors in his text mostly in Chapter 6 (Energy Conservation). Before I read some parts of Classical Mechanics by John Taylor but felt that he is too verbose that is why I have tried to scan other text. Any...

In QFT, all particles can be interpreted as excitations of some fundamental quantum fields in the vacuum. This is the quantum picture. But in classical world, only photons and gravitons have classical counterparts. How to explain this? The common feature of these two is that they are...

Homework Statement I'm working (self-study) through Goldstein et al, Classical Mechanics, 3rd Edition, and I'm currently stuck on Problem 8.11: A particle is confined to a one-dimensional box. The ends of the box (let these be at \pm l(t)) move slowly towards the middle. By slowly we mean...

Homework Statement Around vertical axis ##O## a body on picture below (see attachment) is being rotated with constant angular velocity ##\Omega ##. On the circle we have a body with mass ##m##, that can feels no friction. Find position of that body as function of ##\phi ## and time. Calculate...

Ayo everybody, I'm doing a problem about theory of small oscilatons (see pic) and I got the following for potential energy: V= mg(\frac{l_{2}}{2} +\frac{l_{1}}{2} \theta^{2}_{1} + \frac{l_{2}}{4} \theta^{2}_{2}) (after the aproximation cos \theta ~ 1 - \frac{\theta^{2}}{2} Knowing that V...

Hi all, I'm a first year undergrad and I'm currently struggling with Physics. I aced high school physics (A-levels) but for my first class test at uni, I got a 50% and now I'm not sure if I'll be able to make this to 90%+ during the second class test (in exactly a month from now). We are...

Hello everyone, The problem I am currently working is exactly what is given in this link: https://www.physicsforums.com/showthread.php?t=554243 However, I do not understand why we integrate between 0 and infinity. What is the motivation for doing so?

Homework Statement Hi, this is one the problem on my homework, but I don't know where t start with this problem. We have equation of a particle's potential energy field: U(r)=-GMm/r+Cm/r^2 C is just a constant. I need to solve for its radial motion and angular motion, then if the motion of...

I've been reading, in my own time, a first course in thermodynamics and they present a quantum treatment of statistical mechanics (discrete energy levels), but on the article for the partition function on wikipedia, I find out that there is a classical treatment of statistical mechanics as well...

Hi, I was reading about interference patterns. I was wondering if the classical interpretation of the wavelength of the photon according to maxwell's is the actual wavelength of the photon in the wavefunction? Are the two related? Thanks!

The time has come to schedule for next semester's classes. I will be a senior in physics and choosing some electives. I am trying to decide between taking matrix theory (linear algebra) or graduate level classical mechanics. I really WANT to take the mechanics course but I feel that maybe I...

Hi All, In the Feynman, 'sum over paths' approach to quantum field theory, we compute amplitudes, generating functionals etc by feeding in a "classical action". By calling the Lagrangian that we feed in "classical", this mean that the fields that feature in that action are regarded as...

How is electromagnetism different from gravity in that accelerated objects radiate EM waves when accelerated in an electric field but no gravitational waves are generated when objects are accelerated in a gravity field? Why do not planets orbiting the sun generate gravitational waves and...

Homework Statement for particle with lagrangian L = m/2 dx/dt^2 + fx where x is constant force, what is ScL (classical action) Homework Equations d/dt (∂L/∂(dx/dt)) = ∂L/∂x ScL = ∫m/2 dx/dt^2 + fx dt from ti to tf The Attempt at a Solution d/dt (∂L/∂(dx/dt)) = ∂L/∂x implies f =...

Homework Statement A particle of mass m moves under an attractive central force of Kr^4 with an angular momentum L. For what energy will the motion be circular? Find the frequency of the radial oscillations if the particle is given a small radial impulse. Homework Equations...

One page 24 of his book on classical field theory (4th edition), Landau derives the relativistic equation of motion for a uniformly accelarated particle. How does he get the differential equation that leads him to his result?

I know there are other things that fail about the rutherford atom but as the electron is accelerating and radiating away energy it would fall into the nucleus, my question is how much energy would the electron need to gain so that the classical atom could be stable a hydrogen atom for example

I have a disagreement with a Quantum mechanical scientist about a double slit experiment with polarizers, which gives interference or not depending on "which path" knowledge of the photon. That is alright with me, but I can calculate the same results with classical wave formula. He does not...

Homework Statement A ray of light enters a glass block of refractive index n and thickness d with angle of incidence θ1. Part of the ray refracts at some angle θ2 such that Snell's law is obeyed, and the rest undergoes specular reflection. The refracted ray reflects off the bottom of the block...

In classical physics, charged particles induce electric field ##\vec{E}_c## around them. How do we interpret this classical electric field ##\vec{E}## in quantum mechanics. Is this just the vacuum expectation value ##\vec{E}_c=<0|\vec{E}|0>##? if so, it means ##<A>\neq 0##. This would lead to...

First-Order Extrema in "Classical Mechanics", Theoretical Minimum In the 3rd lecture of Classical Mechanics, 2011, by Dr. Susskind in his Theoretical Minimum series, he talks about calculating extrema, saddle points, etc. to "first order". "if you move a little bit, the potential is zero, to...

I mean many people try to abstract the classical world but isn't it just the accumulation of QM properties that build and break down what appears to be an obvious and intuitive classical world. Does QM outright contradict the classical world or does it explain the base fundamentals of our...

The classical physics developed by people such as Fraunhoffer and Fresnel seems to work very well at predicting the results obtained when observing interference and diffraction patterns. Quantum theory seems to work well also and can be used,for example when photons are sent one at a time...

I know this has been asked before but I am still not getting it. Does anyone know why a classical deterministic world with fixed positions emerges from the statistical distributions IE superpositions of the quantum mechanical world. Why am I nor my tv or dog not in superposition. There is a...

In special relativity we have the invariant spacetime interval ds2 = dx2 - c2dt2. If we think about classical (non-relativistic) space and time as one spacetime in which the transformation between reference frames is given by the Galilean transformation, is there a corresponding spacetime...

In wikipedia it says that "Coulomb's law of electric forces was initially also formulated as instantaneous action at a distance, but was later superseded by Maxwell's Equations of electromagnetism which obey locality." I don't really understand in which sense Maxwell's equations solve the...

I am studying for the mechanics modules of A level mathematics under EdExcel.So far the books seemingly published to support the specifications aren't doing a very good job.The examples in the books don't tell the students how to solve problems in the exercises, which is a sheer let down.I want...

I just took Physics I last semester, but I still feel there is so much more to learn about classical mechanics. I could work on 100 different problems involving binary stars, rockets, or rotating objects - but then a slight twist is thrown in on the problems, then something new to have to...

There's very few problems in Landau's books. I'm the kind of guy that properly learns material by doing tons of problems. Of course I can pull from other textbooks but there's the issue of different notation, extra material within chapters, etc... Does anyone know of a good resource that can...

From (Marion 5th ed. Problem 9-15) A smooth rope is placed above a hole in a table. One end of the rope falls through the hole at t = 0, pulling steadily on the remainder of the rope. Find the velocity and acceleration of the rope as a function of the distance to the end of the rope x...

Hello friends, Why does classical physics not follow a probabilistic nature? And why is conventional predicting absent at microscopic levels? I have searched a little including sites like physics.exchange but only see responses that are "classical physics fails to predict this" or "it cannot...

Hello, There has been lot many articles, write up(s) pointing out the difference between classical and quantum physics. Well, I know that there has been thousand and one articles written on the topic, but my point is to find out the basic fundamental difference. One point is quiet evident...

I am starting University in September, 2014. I have some knowledge already on classical mechanics as I took optional Applied Math courses (called Mechanics 1 and Mechanics 2) in my mathematics A-Level. I am also self-studying the book Classical Mechanics by Goldstein, Poole and Safko to gain a...