# Questions tagged [dissipation]

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### Why does height affect bounce efficiency?

I recently conducted an experiment, where I dropped tennis balls from various heights and recorded their rebound heights. The higher the drop, the higher the rebound height, obviously. However, the ...
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### Work done over a closed loop

Is it true that the work done in the motion of a body over a closed loop is zero for every force in nature?
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### How do resistors generate different heat if we make the current fixed and changed the voltage and resistance? Notice the flow of charge is constant

Consider having a circuit which consists of a battery and one resistor. $V = 10$ volts, $R = 5$ ohms, so $I = 2$ Amperes, and $P = 20$ watts. If we double the voltage and resistance, the current ...
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### Thermodynamics: how does the deformation of partially elastic materials produce heat?

When a perfectly elastic material is deformed, the energy associated with the strain remains stored in the body as elastic potential energy, called strain energy. Upon the removal of the deforming ...
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### Damped forced Oscillation with variable external frequency

Consider that we have the following forced vibration with an input frequency $ω(t)$ variable in time. $$m\ddot{x}+c\dot{x}+kx = F_0 \sin{(\omega(t) t)}$$ Assuming that the solution must be a ...
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### In Feynman lecture Vol1. chapter12 about friction, $F = μN$ will fail because of the excessive heat generated. Why is that?

$F = μN$ will fail because of the excessive heat generated if the normal force or the speed of motion gets too big. Why is that? "$F = μN$, where μ is called the coefficient of friction (Fig. 12-1)....
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### Examples of non-Hermitian Hamiltonians in open systems?

I have often heard the statement that non-Hermitian Hamiltonians can be used to describe open systems, since the dynamics are non-unitary. However, I have not been able to find any examples of a non-...
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### Absence of dissipative forces in a reversible process

I can't understand why dissipative forces must be absent during a reversible transformation. Aren't they a way of exchanging heat with ambient? Since the system is allowed to exchange heat with the ...
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### When is mechanical energy ever conserved for inelastic collisions?

So as I was taking a test today I encountered an intriguing question, the question came in two parts. The first parts, which I answered quite easily, was about whether or not mechanical energy is ...
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### Klein-Gordon/Maxwell Equation: dissipative or dispersive?

In Aspects of Symmetry, Coleman says (p. 185) ''Most of the simple field theories with which we are familiar have the property that all of their non-singular solutions of finite total energy are ...
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### How can dissipative/friction terms be incorporated into a Lagrangian?

I'm trying to find a suitable Lagrangian for a damped harmonic oscillator, a system that satisfies the following equation of motion: $$m \ddot{x} + \gamma \dot{x} + \frac{d\phi}{dx} = 0.$$ What I ...
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### A damped harmonic oscillator is NOT a dissipative system?

I know this sounds rather insane, but it says so in my book. The argument is the following: Given a damped harmonic oscilator $$\ddot{q}+\frac{b}{m}\dot{q}+\frac{k}{m}q=0 \tag1$$ this system can be ...
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### Why don't objects bounce infinitely?

I'm computer programmer, and I was making a little test of my “possibilities”, so to speak, so I made a small game with sort of gravity, bouncing ball and walls around. Recently I've noticed that ...
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### Dissipation and first law of thermodynamics

Consider the following situation: a certain gas is contained in a well-insulated cylinder with a well-insulated piston head. Now, in this case the piston is not frictionless. In order for the piston ...
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### Energy dissipation in current flow

In section 4.8, Energy dissipation in current flow, of Purcell and Morin's Electricity in Magnetism, the expression for the power expended by a resistor is derived. The sections includes the following ...
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### Resonance peak broadening due to losses: physical reason

I wonder why when losses are present in a oscillator, the width of the resonance peak is broadened. More precisely: why, when losses are present, can the amplitude reach nearly the maximal one (the ...
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### How does temperature affect sound wave dissipation in air?

Sound waves dissipate in any material such as air, but if temperature decreases or increases; how would the increase or decrease in temperature affect the dissipation?
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### Work transfer to the contents of an ideal thermos flask

Assuming the thermos to be ideal and the fluid stored inside it also ideal and non-viscous. For a cold fluid, is it possible to increase the fluid's temperature by shaking the thermos flask? Can the ...
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### Hysteresis and dissipation

Hysteretic phenomena are often linked to dissipation. When there is a hysteresis loop, the dissipated energy can usually be computed as the area of the cycle. For example, in ferromagnetic materials, ...
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### Why is it better to accelerate electrons in a linear collider?

An accelerated charge (say an electron for simplicity) emits photons. Changing direction of movement is an acceleration. Electron-positron collisions are preferably done in linear colliders. But why ...
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### Will tsunami waves travel forever if there was no land?

If there was no land for tsunami waves to collide with, can the waves travel around the globe for forever?
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### What happens with the energy released after a particles collision?

From the website of CERN: "Collisions in the LHC generate temperatures more than 100,000 times hotter than the centre of the Sun.". My question is, what happens to the energy released after the ...
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### What is wrong with my perpetual motion machine model? [closed]

I know that perpetual motion machines are not possible and I want to know the reason why will this machine not work. The Car B has a magnetic bulge on top of it and Car B can only move forward. It ...
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### Where exactly does the drag force come from when using eddy currents?

I read the Wikipedia page on eddy currents and the explanation for braking confused me At the leading edge of the magnet (left side) by the right hand rule the counterclockwise current creates a ...
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### Perpetual Motion Machine 1: Magnetic Superconductor Loop Generating Energy with Piezoelectrics [closed]

I know there are a lot of perpetual motion machine designs out there, but I haven't found one that looks like this one. I will use this diagram. Assume the entire ring is made of a superconducting "...
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### Potential, Kinetic, Thermal Energy?

When things move, potential energy turns into Kinetic energy, right? Then how does Kinetic energy convert to thermal energy?