# Questions tagged [classical-mechanics]

Classical mechanics discusses the behaviour of macroscopic bodies under the influence of forces (without necessarily specifying the origin of these forces). If it's possible, USE MORE SPECIFIC TAGS like [newtonian-mechanics], [lagrangian-formalism], and [hamiltonian-formalism].

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### Connection between dispersion relation and symmetries of the Hamiltonian

I am having trouble understanding intuitively the connection between the dispersion relation and the symmetries of the Hamiltonian. For example, suppose we have a lattice and there are four sub-...
1 vote
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### Does electric and magnetic field from electromagnetic radiation are 2D based? [closed]

I'm getting into physics, specially in electromagnetism. When we're talking about electromagnetic radiation. Does it has a 2D shape when it's propagating through space? Does Maxwell's equations ...
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### Strogatz's condition on definition of energy

In, Nonlinear Dynamics And Chaos, 2nd edition page 160, by Steven H. Strogatz, he writes Let’s be a bit more general and precise. Given a system $$\dot x =f(x),$$ a conserved quantity is a real-...
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### What is the relationship between phase space and Jacobian in Nakahara Eq.1.15 (under this equation)?

In Nakahara's Geometry, topology and physics, under Eq.1.15 they give an equation \begin{align*} \det\left(\frac{\partial p_i}{\partial\dot{q}_j}\right)=\det\left(\frac{\partial^2L}{\partial\dot{q}_i\...
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### Does quasi-symmetry preserve the solution of the equation of motion?

In some field theory textbooks, such as the CFT Yellow Book (P40), the authors claim that a theory has a certain symmetry, which means that the action of the theory does not change under the symmetry ...
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### Work Done by kinetic friction in Circular Motion

We know when an object is moving in a circular motion on a rough horizontal surface, direction of kinetic friction is constantly. Thus, fto calculate the work doen by friction, we need to use ...
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### I need an explanation for the time derivative omissions when solving for the Lagrangian of a system [closed]

So I have been self-studying Landau and Lifshitz’s Mechanics for a little bit now, and I have been working through the problems, but Problem 3 is giving me some trouble. I solved the Lagrangian ...
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### Question regarding gravitational force as external force

So, I was watching a lecture on YouTube for problems on conservation of energy and momentum and I don't quite understand this: In this question, mass $M$ is released from the peak of the smooth ...
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### I am trying to derive an expression for the magnetic field of charged particles travelling at significant fractions of speed of light [closed]

I tried using lorentz transformation , which gives me correct answer for speed of light c but when i try to input any other values nearby c it becomes a constant B = 10-7 . q/r² ( (v - u)/ 1- uv/c²)
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### Justifying that the gold nucleus is at rest in a Rutherford experiment

This is an example on the Rutherford Experiment from Young and Freedman's University Physics. In the last paragraph of the solution the book states that it is valid to assume that the gold nucleus ...
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### Is it possible to understand in simple terms what a Symplectic Structure is?

I would like to understand what a Symplectic Structure is, and its implications in Classical Mechanics (Phase Space), but in pre-grade terms (If that could be possible). I have not taken any ...
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### Diffusive momentum transport as overlap of acoustic peaks?

In the context of molecular dynamics simulations of soft or hard spheres in the fluid phase (e.g., with Lennard-Jones interactions), it is known that the velocity autocorrelation function (VACF) ...
1 vote
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### Massless String Having Different Tensions

I'm a student fairly new to physics, and I was working through a textbook (this is not for homework) when I came across a problem involving Two masses, $m$ and $2m$, hang over a pulley with mass $m$ ...
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### The conservative force [closed]

I read about the definition of the curl. It's the measure of the rotation of the vector field around a specific point I understand this, but I would like to know what does the "curl of the ...
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### Action-angle variables for three-dimensional harmonic oscillator using cylindrical coordinates

I am solving problem 19 of ch 10 of Goldstein mechanics. The problem is: A three-dimensional harmonic oscillator has the force constant k1 in the x- and y- directions and k3 in the z-direction. Using ...
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### Can a translational torque cause a change in rotational angular momentum? gyroscope example

Please confirm if my understanding is correct: The example of a gyroscope suspended from a pivot is a case in which translational torque causes a change in the direction of rotational angular momentum:...
1 vote
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### Vanishing virtual work done by non-holonomic constraints

I was reading classical mechanics by NC Rana. I was reading a topic on vanishing virtual work done due to constraint forces. How do you prove that the virtual work done by non-holonomic constraint ...
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### Why does my curry "bounce back" after stirring?

I recently cooked a big pot of curry, consisting largely of coconut milk, a bit of chicken stock and some vegetables. You can probably imagine that it was somewhat thick in consistency. The cooking ...
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### Is the Virial Theorem dependent on the classical Equipartition Theorem?

The Wikipedia entry for the Virial Theorem states: "*The significance of the virial theorem is that it allows the average total kinetic energy to be calculated even for very complicated systems ....
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### Generalized momentum

I am studying Hamiltonian Mechanics and I was questioning about some laws of conservation: in an isolate system, the Lagrangian $\mathcal{L}=\mathcal{L}(q,\dot q)$ is a function of the generalized ...
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### What's the need for 2 separate laws of motion when the first law is an special case of the second one? [duplicate]

The first law of newton tells us that a body shall remain unaccelerated when the net force acting on it is 0, but the second equation gives us the relation F=ma so, ain't the first law just an special ...
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1 vote