Classical Definition and 1000 Threads

Homework Statement A particle of mass m is subject to a force F (x) = -kx. The initial position is zero, and the initial speed is v0. Find x(t). Homework Equations F = m*v*dv/dx = -kx v = dx/dt The Attempt at a Solution I'm new to differential equations, so please excuse me if I make any...

Hi! first time poster here. I'm making an orbital simulation and I am having a problem with one minor detail. The gravity is working great, and I've programmed it using this formula: A force vector is applied = DirectionOfCentralBodyNormalized * ((GravConstant * centralbodymass *...

An isolated mechanical system can be represented by a point in a high-dimensional configuration space. This point evolves along a line. The variational principle of Jacobi says that, among many imagined trajectories between two points, only the SHORTEST is real and is associated with situations...

Here is a link to a derivation of classical intrinsic angular momentum: https://www.scribd.com/document/349675642/Potential-energy-Prop-to-SL In 2.1 in the image above they define: ##m=2\mu S## and say that ##\mu## is the bohr magneton. By using the defintion of the bohr magneton I get...

hilbert2 submitted a new PF Insights post Damped Motion in Classical and Quantum Mechanics Continue reading the Original PF Insights Post.

Hey guys! I'm currently on my junior year and I will be taking advanced classical mechanics next semester. My lectures will consist mainly on Lagrangian and Hamiltonian mechanics and I am currently in need of a good book in classical mechanics. I have used Kleppner and Kolenkow's An Introduction...

Phase volume is it the same as the number of total microstates in some physical system? Phase volume= volume of phase space. Or there is some difference?

Hey guy, I'm a just new in physics and i want to self-teaching it. But i don't know what calculus i need for classical mechanic. Pleas help! And if you suggest me a book can you pleas help to send me a link (and the book must be in pdf pleas) Thank

Hi people. Here the situation. Balloon filled with air I throw in the air. Balloon starts to move upstairs. It slows down and then is starts to fall down to the Earth. I'm interesting only in the movement of upstairs. Here the picture. In the first case (left) I choose the direction of...

In Quantum Mech. we learned about classical uncertainty, and then Heisenberg's uncertainty principle which comes from it. The way it is in the book is, the preceding chapter talks about how the superposition of lots of waves ∑ gives you these groups, and things like group velocity comes from...

Hi all, I am looking for a good introduction to classical mechanics. I have looked at some book recommendations online but I am having trouble choosing the right book for me. Right now, I know no physics, so I need to start from the very beginning which I think is classical mechanics. I am self...

I am aware that in classical electrodynamics a metal exponentially attenuates TEM waves. I am wondering if this fact is sufficient to obtain estimates of the cross section of low energy gamma rays in metals. Obviously it would fail for higher energy gamma rays where Compton scattering and pair...

Hi, i would be curious to know what would be the prerequisites for learning the classical field theory !

I need a book written just on the style of Classical Mechanics by Goldstein. I don't remember the book name and author but it is just the copy of the book Classical Mechanics by Goldstein. Please guide.

In QFT, one can derive the equations for particles interacting electromagnetically by demanding phase invariance for the field when writing down the free field lagrangian for the klein-gordon or dirac equation. Question: Does classical EM follow from this method also? (At least theoretically...

i'm trying to understand the solution to this problem: http://physweb.bgu.ac.il/COURSES/StatMechCohen/ExercisesPool/EXERCISES/ex_2065_sol_Y13.pdf (link to the problem and the solution of it) All my questions come from the partition function: 1) From where the term (2*pi)^d comes from?, I...

Let us consider a classical field theory with gauge fields ##A_{\mu}^{a}## and a scalar ##\phi^{a}## such that the Lagrangian is gauge-invariant under the transformation of 1. the gauge fields ##A_{\mu}^{a}## in the adjoint representation, with dimension ##D_{\bf R}##, of the gauge group...

In this thread I gather my questions concerning derivations in the textbook of equations and of solutions to the exercises. I hope every student and professional will benefit from this thread. I'll start in the next post.

I'm currently working (slowly) through Goldstein (et al), 3rd Edition, and a remark in the section on Action-angle Varibles for Completely Separable Systems (10.7) is giving me pause. We're told that the orbit equations for all ##(q_i, p_i)## pairs in phase space describe libration or periodic...

In classical field theory, translational (in space and time) symmetry leads the derivation of the energy-momentum tensor using Noether's theorem. From this it is possible to derive four conserved charges. The first turns out to be the Hamiltonian, and thus we have energy conservation. The...

I'm interested in understanding the key physical differences between classical and quantum dynamics. I understand that spin (intrinsic angular momentum) is one major physical difference.* So I wonder whether all else flows from this? Or are there other major (unrelated) physical differences...

QM is often thought to be strange due to contextuality - the fact that measurement outcomes depend on measurement itself. Today a nice paper http://lanl.arxiv.org/abs/1703.07550 appeared that presents a classical analogue of quantum contextuality. I hope it can help to make contextuality look...

Homework Statement I'm a pharmacologist and I have a modern physics course to do. This is not my field and I'm completely lost... We were given this problem to do. Thanks a lot in advance. Consider a potential where U(x) = 0 for x ≤ 0 U(x) = -3E for x > 0 Consider a particle of energy E...

I composed a problem and propose it here. I know the solution so it just for fun of the participants. There is a cylindrical bobbin of radius ##r##; the bobbin rotates about its central axis with angular velocity ##\omega=const>0##. An inextensible weightless string is coiled around the...

Is a classical universe (with a deterministic dynamics) compatible with assuming that experimental choices can be made arbitrarily? This question arises from the following statement of Bell: that I had cited (with a reference) in https://www.physicsforums.com/posts/5694545/, and commented...

Hi, So I can get the idea that the ac current in a radio transmitter produces radio waves of the same frequency of the ac supply, just like shaking a slinky sprung up and down but how does this translate into the radio waves as actually coming out as photons and for that matter other than...

Homework Statement hi i was doing a practice physics junior olympiad paper when i got stuck in question 11 in this link [/B] https://www.scribd.com/document/244111815/SJPO-2013-Special-Round-pdf Edit by moderator: Inserted relevant extract of the PDF so that helpers do not have to...

I have a question regarding the ontology of the many-worlds interpretation which by my assumption shows some deficiencies in this way of thinking. When many worlders describe branching and effects giving rise to multiple worlds they typically invoke Schrodinger cat-type experiments where from a...

I would like one that is not very mathematically intense, and not to advanced, thanks for any replies.

Suppose we are talking about a purely classical phenomena (OK, nothing is purely classical, but suppose we consider quantum effects as insignificant, that is, we ignore them). In this context, I came across someone talking about "a particle in chaotic continuous motion as the particle is...

Hi I've been wondering about Boltzmann's equation S = k ln W Where W is the number of different distinguishable microscopic states of a system. What I don't get is that if it's the position and velocity of a particle that describes a microstate doesn't it mean that W would be infinite...

good morning, I'd like to know if exsists a classical explanation and, of course, qualitative about the nuclear fission / fusion reactions. I would like to explain the development of external energy to considering only nuclear forces system in terms of internal mechanical energy and the fact...

Homework Statement Hello! I apologize for my poor setup, first post. I am given a system of two rods, hope you can see my image.http://file:///C:/Users/Mikkel/Downloads/Mek2_exam_Jan2016_final.pdf One along the x-axis with mass = 2m and length = 2l Another perpendicular with the other with...

Quantum mechanical foundations are usually phrased in terms of measurement. I believe this is the main cause why these foundations remain shaky after almost 100 years of a good mathematical basis. Classical mechanics never had any reference to measurement in its foundations, and hence it was...

Homework Statement Hello, I solved others but not 6.9: Find the equation of the path joining the origin O to point P(1,1) in the xy plane that makes the integral ∫(y'2 +yy' + y2) dx stationary. ∫ from O to P. y' = dy/dx Homework Equations I need use ∂f/∂y = d/dx (∂f/∂y') (euler-lagrange...

For some time I've been wondering how to eloquently distinguish classical and quantum physics. What I mean by eloquent is both simple and short. By simple I mean understandable to any college freshman, and with that caveat, as short as possible. Something like: "quantum has inherent randomness...

I am a high school student looking for some amazing lectures online to study classical mechanics for a regional qualifying camp for ipho.

Homework Statement An object of mass m = 300g is attached to a spring with a constant k = 3.0Nm-1 and is at rest on a smooth horizontal floor in a fluid where the resistive force is assumed to be linearly proportional to the velocity v. the object is then displaced 10mm to the right of the...

Hi, when do we use hamiltonian vs. Newtonian mechanics or even lagrangian formulations? pros and cons? I am thinking molecular dynamics codes

Hello everyone. So I wanted to get some opinions on what some of you thought was a better choice, as far taking PDE's or classical mechanics 2 goes. First let me start off by giving a little info; I've already taken calc 1-3 and ordinary differential equations, physics 1 & 2...

The velocity versus time graph is the following: http://imgur.com/kyebx8H As the title asks, how would you find the maximum force on a velocity vs time graph given nothing but the graph and the mass of the object in question. My reasoning was that since f = ma and m is never changing, that...

http://onlinelibrary.wiley.com/doi/10.1002/lpor.201500252/abstract https://arxiv.org/pdf/1509.06217v2.pdf "...it has been implicitly assumed that this scheme is of inherently nonlocal nature, and therefore exclusive to quantum systems. Here, we experimentally demonstrate that the concept of...

Classical fields are usually constructed using a collection of classical harmonic oscillators, e.g. masses connected to springs. The energy of a classical harmonic oscillator is proportional to the amplitude squared. QFT uses quantized versions of those same classical fields. But, in the...

Under what condition would particle de Broglie wavelength be equal to the classical EM wavelength?

Hi, What book could you recommend for a first course in classical electrodynamics? Thank you

Homework Statement A spherical satellite of radius r is moving with velocity v through a uniform tenuous atmosphere of density ρ. Find the retarding force on the satellite if each particle which strikes it (a) adheres to the surface and (b) bounces off it elastically. I know the answer should...

Some time ago I tried to define classical inverse-square gravity on a 3-dimensional (cubical) torus T3: the quotient space obtained by identifying opposite faces of a unit cube. (Or more rigorously, the quotient space T3 = R3/Z3 of R3 by its subgroup Z3 of integer points.) I assumed there...

This question was asked in an competitive exam in India. The relevant equations are momentum conservation in the classical sense and the 4 momentum conservation. My attempt: Classical momentum conservation would seem inaccurate since the kinetic energies are high. However, a straightforward...

I've added 'in classical physics' in the thread title because all the differences between them that I found on the internet involved relativistic physics. It was something like both momentum and kinetic energy being components of a four-momentum or something like that. But I cannot understand...

Homework Statement how from this question using Energy principles I can find how frequency depends on g? Homework EquationsThe Attempt at a Solution I know that frequency is sqrt(k/m) this is a formula you use in introductory physics. but I am lost on how to do it from energy route or...