# Tagged Questions

Classical mechanics refers to the classical (i.e., non-relativistic, non-quantum) study of physics. Three major formulations of classical mechanics are newtonian mechanics, lagrangian mechanics, and hamiltonian mechanics. The latter two are rather useful in extensions to Classical Mechanics; ...

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### basic question about work exercise

I am learning independently from Tobochnik's statistical physics text. He asks a warm up question about work: A person pushes a block up a frictionless ramp. Is the work positive, negative, ...
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### Force dependence on velocity : Drag

I just listened to the second lecture of Leonard Susskind on classical mechanics where he discussed that force can't be proportional to velocity, since it's unable to retro-dict (predict past). He ...
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### Motion of water droplets on airplane window during takeoff

I observed this while on a flight that took of shortly after it had rained, but could not understand why it happened. The windows of the aircraft had drops of water on the outside. As the flight ...
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### Movement of a box containig a particle [on hold]

A small thought experiment: Imagine a rectangular box in space, containing particle, all resting at $t=0$ from your point of view. At some point in time $t>0$ the particle starts to move with ...
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### Numerical solution of Duffing’s equation [on hold]

Any one can help me with the Numerical solution of Duffing’s equation on urgent basis as i need this for my exam.
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### Movement of a bobbin thread when pulling it's thread at certain angles [on hold]

The problem: You try to move a bobbin thread by pulling it by it's thread. If you pull it while the thread is horizontal it slides your way but if it is at an angle the bobbin thread starts rolling ...
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### A brief idea about Noether's Theorem? [closed]

I've recently been lead to believe that a certain "Noether's Theorem" could prove to be a very helpful tool in physics. I've only just started reading up on Lagrangian mechanics, but I'd like to get ...
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### Classical Mechanics as an approximation of Quantum mechanics [closed]

I want to show an equality: We know from Ehrenfest's theorem that $$\frac{d \langle x \rangle(t)}{dt}= \left\langle \frac{\partial H}{\partial p} \right\rangle$$ I'd like to derive the ...
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### Why does the colour inside a discharge tube change as pressure reduces?

Observing cathode ray tubes at various pressures, I see a transition from a violet/purple colour at 10-40mmHg, transition to a white/light blue colour at lower pressures. Any idea why this happens? ...
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### counting normal modes

I'm not sure if my confusion is substantive or merely semantic. So here's the most naïve way to frame it: A free $N$-atom molecule has $3N-6$ vibrational normal modes, with each mode having fixed ...
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### Can I give a table tennis ball enough spin so that it rolls further on the other side instead of bouncing?

If I give a table tennis ball enough topspin, is it possible that the ball on touching the other side of the table doesn´t bounce, but just rolls further?
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### Reason behind Poincare's generalisation of the law of inertia

In Poincare's Science & Hypothesis [Chapter 6], he starts with Galileo's famous ($1$) Principle of Inertia — A body acted on by no force can only move uniformly in a straight line. He then ...
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### a/x^2 + bdx^2 analytical solution [migrated]

I have this physics problem I'm trying to solve and its been a while since I've done differential equautions. The problem I'm trying to solve is : ...
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### Pseudo acceleration when both observer and observed body are accelerating and also the surface is accelerating

Today we were taught us the concept of pseudo forces.I understand that suppose when the observer is in an accelerated reference frame to make newtons laws valid we consider an acceleration in the ...
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### Examples of multiply-connected compact configuration spaces

I'm a looking for examples of dynamical systems that have multiply-connected compact configuration spaces. Since I'm not a 100% sure about the correct terminology for the systems (I am sure about the ...
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### In quantum mechanics, how exactly do we associate Hermitian operators to classical observables? [duplicate]

In a first course on quantum mechanics, everybody learns some version of the following statement: Postulate: To every classical observable $A$ of a physical system, there corresponds a Hermitian ...
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### Composite materials [closed]

I'm reading about brake pad material. The paper said ...according to original equipment manufacturer (OEM) the pads are made by combining five types of materials: binders, abrasive, performance, ...
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### Geometric point of view of configuration space and Lagrangian mechanics

Even though (I think) I understand the concept of a tangent bundle, I have trouble assimilating the idea of the configuration space being one and in relation to what that is the case. How can I ...
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### What enclosed geometry amplifies sound the most?

I am going to build a record player. It will read sound electronically but I also want it to be able to project sound mechanically, like a classic record player. So if sound enters a tube, can you ...
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### Why do molecules have $3N-5$ or $3N-6$ degrees of freedom?

In linear molecule, it has $3N-5$ degree of freedom in vibration mode and $3N-6$ in non-linear molecule. I can get idea about $5$ and $6$ which is related to translation and rotation but I cannot ...
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### Chromatic confocal microscopy (CCM) and stylus probe

I read research that compared between chromatic confocal microscopy (CCM) and stylus probe in wear test but the research didn't clearfield what is chromatic confocal microscopy and what is the stylus ...
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### The directions of the frictional force acting on the cylinder while ascending and descending cylinder

A cylinder rolls up an inclined plane,reaches some height,and then rolls down without slipping throughout these motions.The directions of the frictional force acting on the cylinder (A)While ...