Questions tagged [dissipation]
The dissipation tag has no usage guidance.
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Friction on a rolling body [duplicate]
I have been reading about rolling motion and I seem to have a confusion regarding the friction acting on such bodies.
First off for a body to start rolling their has to be some friction b/w the ...
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If energy is conserved, why do we need to save energy?
The conservation of energy says that it can neither be created nor be destroyed, it can only be transferred from one form to another. i had this doubt in my mind for a long time that why do we need to ...
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Fourier Transform of Damped Oscillations - Zero Frequency Peak and Shift [duplicate]
A damped oscillator has the time evolution:
$$ y(t) = e^{-\Gamma t}\cos^2(\tilde{\omega}_0 t)$$
where $\Gamma$ is the damping rate, $\tilde{\omega}_0^2=\omega_0^2-\Gamma^2$ and $\omega_0$ is the ...
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How to determine structure stiffness of a damped 1D system with acceleration - time graph?
Consider a damped system with only acceleration - time data is available, how to determine the structure stiffness (k)? Mass of the structure is also known. It moves in a horizontal direction, like a ...
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Equations of motion for two masses connected by the Kelvin-Voigt Model
I have a system where two particles $x_1$ and $x_2$ in one dimension are connected by a spring and a dash in parallel. This is analogous to the Kelvin-Voigt model for viscoelastic materials. The two ...
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Relation between power dissipation and imag part of susceptibility [duplicate]
I am trying to understand the following relation between power dissipation and the imaginary part of the susceptibility, from Sethna's Statistical Mechanics textbook. Why does the integral equal the ...
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Conditions for the existence of a steady state in time-driven system
Consider an open quantum system given by the Hamiltonian
$$H = H_B + H_S(t) + H_{SB}$$
with $B$ denoting the noninteracting bath, $H_S(t)$ the time-dependent noninteracting system and $H_{SB}$ is a ...
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Pushing a Hamiltonian part into dissipative part in Lindbladian
Suppose we have the following Lindbladian:
$$\mathcal{L}(\rho) = -\frac{i}{\hbar}[H, \rho] + \sum_\alpha L_\alpha \rho L_\alpha^\dagger - \frac{1}{2}\{L_\alpha^\dagger L_\alpha, \rho \}.$$
Suppose we ...
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How does energy conversions happen in the circuit?
Let's imagine that we have battery connected to wire and the only component in circuit is light bulb and let's say we got 5V in battery. I'm looking for the intuitive explanation and not with the ...
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Amplitude of a Damped Harmonic Oscillator
Background: What I know about simple harmonic oscillators
For a simple (undamped) harmonic oscillator, one expression for the position as a function of time is
$$
x(t) = x_0 \cos(\omega_0 t) + \frac{...
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Would sound get weaker in metal faster than in air over the same distance?
I'm finally closing some gaps in sound waves, so forgive me for lots of questions.
In metal, it's said sound travels fastest. The reason is molecules are tightly packed(more dense) in metals than in ...
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Why sound gets weaker as it travels in air? [closed]
When we talk, our vibrating chords oscilate next air molecules which oscilate the next molecules and so on. Hence sound wave travels.
As we know, energy that reaches the destination is not the same ...
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Theory of conserved quantities in damped systems?
As is well-known, classical conserved systems have conserved quantities by virtue of continuous symmetries, which can be derived from Lagrangian mechanics. For example, two masses on a spring can swap ...
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Why resistors consumes power? [duplicate]
this is a basic voltage divider circuit. Whenever electrons are about to enter in $R_2$ they have some energy. And when they leave R_2 their energy level decreases.
what kind of energy we are talking ...
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Energy conservation in a forced spring-mass-damper, off of resonance
I understand that at resonance, a spring-mass-damper system will only require input energy from a forcing that matches the energy dissipated per cycle by the damper.
Let's say that you have a system ...
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Conserved quantities in overdamped dynamics
I have an implementation of over-damped Brownian dynamics, with particles that follow the version of the Newtons law where the inertia is absent. This is a common thing to do at micrometer scale.
$m x'...
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What is the relationship between quantum dissipative system and quantum impurity system?
Now I'm studying the phase transition of the many-body system as a school degree.
What I'm curious that, I found the meaning of quantum impurity system is : One particle interacts with an ensemble ...
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Why wouldn't this perpetual motion machine work? [closed]
The water is supposed to run infinitely in this container, since when water drops the pressure inside the container decreases, which makes the water in the pipe ascend. I know that perpetual motion ...
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Occurrence of *critical* damping
I am trying to understand the origin of some transient signals the vast majority of which have shape $(t/\tau) \exp(-t/\tau)$ for $t\gt 0$. This is notoriously the impulse response of a critically ...
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Energy conservation in a driven harmonic oscillator
The ODE for a driven harmonic oscillator is given by
$$
\ddot{x}+2\gamma \dot{x}+\omega_0^2 x = \frac{F}{m}\cos(\omega_dt)
$$
By assuming balance of forces, i.e. energy conservation, one can solve for ...
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Expressing non-Hermitian Dynamics in general and in the Heisenberg picture
Suppose I have an open system governed by a master equation
$$\frac{d}{dt}\hat{\rho} =-i\left[\hat{H},\hat{\rho}\right]+\gamma\left(2\hat{J} \hat{\rho}\hat{J}^{\dagger}-\hat{J}^{\dagger}\hat{J}\hat{\...
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Damped oscillation experiment - damped harmonic motion
Does anyone know of any easy experiments to do that involves damped spring harmonic motion? Preferably an experiment in which I vary variable A and examine how it affects variable B.
I was thinking of ...
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Why does audio signal amplitude always fall off at higher frequencies?
In the frequency spectrum of every real audio sample that I've ever seen, the amplitude of the frequency components is always higher at low frequencies, then rapidly falls off at higher frequencies.
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How would you experimentally determine the damping coefficient of a system?
We have a suspended beam that we need to determine the natural frequency, and more importantly the damping, of. To avoid resonance.
The geometry of the beam is a little too complex to rely on theory ...
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In theory, would amplitude keep increasing forever in an oscillating system in resonace?
Because there is a limit in experiments modelling resonance, the amplitude of oscillation will eventually reach a limit. However, in theory, if there wouldn't be any limitations in the set up of the ...
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Power consumed by an electrical load
I saw this quote on a website recently:
"A fundamental law of electric circuits is, that because current must be constant all the way around a circuit, only half the power of a generator can be ...
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Transient power spectrum of a damped, driven simple harmonic oscillator (DDSHO)
Our prof in the class mentioned something called the transient power spectrum of a damped, driven simple harmonic oscillator (DDSHO). Assuming that we're given the drive frequency, and we're to find ...
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Why does hot water in a hot flask later cool? [duplicate]
What make hot water cool in thermos flask since it doesn’t release energy?
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Does energy conservation law conflict with Active Noise Cancellation
Assume the picture below:
From inlet port In1 and In2 we can have electromagnetic or acoustic energy entrace single sine wave with same amplitude and frequency. Assume we have aligned the waves to ...
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Will an ideal bouncing ball ever stop bouncing?
By an ideal ball I mean a bouncing point mass with the property that it loses half of the velocity (50%) after each bounce. Now according to my definition of ideal ball, it is impossible for the ball ...
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Is tidal energy an infinite source of energy?
As tidal waves are caused due to gravitational force which acts infinitely until the presence of mass (the Moon) which make me think of an infinite source of energy. So what's wrong in here?
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Why wouldn't this perpetual motion machine based on Archimede's principle work? [duplicate]
I found this today on the interwebs:
Obviously this cannot work, but what bugs me is that I cannot figure out the part that would stop it and bring it to equilibrium. I suspect that it has to do ...
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Is 100% of the energy consumed by a light bulb eventually converted into heat?
I understand that any light bulb, whether incandescent or LED, transforms a part of the energy it consumes into heat and the rest into radiation (mainly visible light).
Assuming a 10W LED light bulb ...
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Solution for Phol's pendulum (forced and dampened harmonic oscillator)
The equation of motion for the forced and dampened harmonic oscillator for Phol's pendulum is the following:
$$I_{zz}\ddot{\phi}+b\dot{\phi}+k\phi=M_0\cos{(\omega t +\phi_0)}$$ or $$\ddot{\phi} + \...
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Do I have the correct intuition behind the general dissipation function for Lagrangian Mechanics?
I am reading these lecture notes, section 2.7.1.
The general dissipation function is given via a dissipative force:
$$
\vec{F}^{D} = -\mu(v)\frac{\vec{v}}{v} \tag{2.269}
$$
The Professors references A....
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Measure-preserving vs. non-dissipative vs. Hamiltonian systems
Are measure-preserving systems always non-dissipative? Phase space volume is preserved in both, according to Liouville's theorem. But are there any differences?
Are measure-preserving and non-...
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How to find the distance travelled by a pendulum powered car? [closed]
I'm having trouble finding an equation that find the distance travelled by a pendulum powered car based on the weight of the pendulum bob, the length of the pendulum and the angle where the pendulum ...
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Energy loss in transformer
There is energy loss in transformer due to Eddy current,leakage of flux and resistance of coils . But we assume in calculation a ideal condition. So if there is pure inductor then how could power ...
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Hamilton's equations of motion for damped oscillator
Consider a parallel RLC oscillator. Kirchhoff's equations of motion are
$$
\ddot{\Phi} + \frac{1}{\tau}\dot{\Phi} + \omega_0^2 \Phi = 0
$$
where $\tau = RC$ and $\omega_0 = 1 / \sqrt{LC}$.
What is ...
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How is maximum amplitude of resonance achieved?
Lets take a simplest case of a narrowly tuned system and the outside force exactly at the natural frequency of it. The first pulse will go through, bounce back somewhat weaker and get reinforced by ...
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Are Viscous Resistance and Viscous force the same thing?
Poiseullie’s Formula tells us about Viscous Resistance which confused me that if viscous force and viscous resistance are the same thing?
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Why damping affect natural frequency of simple harmonic motion? [duplicate]
I am curious about that since damping will not affect frequency of SHM, then why it does affect on the natural frequency of the SHM. In the resonance damping graph the peak amplitude become lower but ...
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A pendulum in a superfluid
Imagine to submerge a pendulum in a supefluid. Of course we assume an ideal pendulum, whose joint does not freeze or deteriorate due to the extremely low temperature. We also assume the superfluid to ...
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Force opposite to velocity vector in Hamiltonian formalism
Consider a system on which a force acts opposite to the velocity direction. We can write its equation of motion such as
$$
m\ddot{\vec{x}} = -F\hat{v}
$$
where the non-conservative force $F$ and the ...
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Is a superconductor 'perfect'? i.e. does current flow forever without decaying? [duplicate]
In a (say) circular superconducting loop which has a current initially induced in it, and without any further external influences, and at a temperature above 0 K and below the transition temperature, ...
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Yet another perpetual motion machine: does this imply large selective membranes are not possible? [closed]
So I was just thinking about the buoyant force and came up with what seemed like a simple perpetual motion based on it. Obviously such things are not physically possible so I'm trying to figure out ...
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What does it mean for $\omega$ to not be "real" in practice?
I am reading about landau damping and the author states that $\omega$ is never real (due to collisions).
https://cds.cern.ch/record/1982428/files/377-404%20Herr.pdf
\begin{equation}
1 + \frac{\...
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Piano on the moon
Imagine a piano on the moon. You strike a chord. Since there is no atmosphere, there is no medium for the sound to travel. so where does the sound energy go? Does it just dissipate as another form of ...
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Is David Tong incorrect in this remark about classical mechanics in his QM lectures?
In page 11 of his Quantum Mechanics lectures, we have the following quote:
It turns out that not all classical theories can be written using a Hamiltonian. Roughly speaking, only those theories that ...
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Do we have to take the dissipation function for the whole system?
In lagrangian formalism, The L also known as the lagrangian is taken account of the whole system, for each of its components and parts!
Is this the same for the Rayleigh Dissipation Function?
Like If ...
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