Questions tagged [equilibrium]

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493 questions
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oil and water- The Archimides' law

I have a problem as on the topic, see the below. First I added $25\hbox{cm}^3$ water in to a beaker. Then I added $2N$ oil onto it. But the level of the water was still $25\hbox{cm}^3$. My problem ...
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Brownian motion and equilibrium

I would like to know if when you consider a system in which you have Brownian motion if it is considered a system in equilibrium or far from equilibrium and why. i.e., is Brownian motion considered as ...
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Collisions in System in Equilibrium

Are all collisions between gaseous molecules and boundary in a system at Equilibrium, elastic? Why?
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If ice water equilibrium exists at 0C at 1atm then why don't oceans stay near freezing all time

The arctic ice is basically a giant floating sheet of ice laid upon the ocean so the ocean and ice are (probably) at equilibrium in the arctic. And since all oceans are connected shouldn't all of them ...
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Is there anything in the universe that is completely static? [closed]

Based on my current, admittedly deficient, understanding of physics everything in the universe is in constant change and motion. Is that understanding correct or is there something that is static? ...
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Conceptual Question about Suspension Bridge Forces

Two walkways are suspended from vertical rods. In the first scenario, one long rod supports both walkways and is attached to the ceiling. In the second scenario, two shorter rods are attached to each ...
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How long does it take for a balloon to deflate?

Since gas flows from an area of high pressure to low pressure, upon opening an aperture on say a balloon one would expect the contents to diffuse out until both the inside and outside reach a pressure ...
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Thermodynamics - thermal equillibrium

If I got a heat source (water at $100^oC$), the heat reservoir (infinite lake with the temperature $5^oC$) and my thermodynamic process proceeds at $20^oC$ somewhere above the source. The process is ...
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What is the meaning of free energy out of equilibrium?

So in statistical mechanics the free energy $F$ (either canonical or grand canonical) can be found from the partition sum $\mathcal{Z}$ as: $$\mathcal{Z}=\exp(-\beta F).$$ As far as I can read it ...
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Electric potential definition last portion

The amount of work done in carrying a unit positive charge from infinity to a point in the field against field keeping electrostatic equilibrium. What does it mean "keeping electrostatic equilibrium"?
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How to determine the increment term of normal and shear stress in infinitesimal cube ?

Consider a solid body, if it is in equilibrium then every infinitesimal part of the body is in equilibrium so i take an infinitesimal cube with side lengths, $dx$, $dy$ and $dz$ and try to write the ...
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What is the state of the equilibrium for a second derivative equal to zero?

Considering a potential energy of $U$, and a displacement of $x$, the force is given by $F=-\frac{\partial U}{\partial x}$. Since equilibrium is defined as the point at which $F=0$, we can express ...
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Why are there time averages in the virial theorem if one of its hypotheses is that the system is in equilibrium?

Why are there time averages in the virial theorem if one of its hypotheses is that the system is in equilibrium? According to my textbook, the virial theorem is that for a gravitationally bound system ...
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Stationary particle (quantum)

Setting the potential oprator to zero in the Schrodinger Equation gives us the description of a free particle. Will setting the momentum operator (squared) to zero gives us a meaningful description ...
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Same Charge or Same Potential?

I was studying about sharing of charge between two charged conductors when I came across this statement - When two conductors are joined together through a conducting wire, charge begins to flow ...
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How are the Lagrange points determined?

According to Hyper Physics, there are 5 equilibrium, or Lagrange points of the Earth-Moon system and only 2 of them are said to represent stable equilibrium points. This made me think if there is an ...
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Situation of Stable, Neutral and Unstable Equilibrium

Recently, I was reading about stability of equilibrium. I came across the definitions for different types of equilibrium. Neutral Equilibrium: The kind of equilibrium of a body so placed that when ...
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Entropy irreversibilities

How can we say that a system is reversible or irreversible if not stated? I encountered a book example wherein a piston cylinder device encounters an isobaric process and experiences a transfer of ...
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Equilibrium in Electrostatics

In case of electrostatics,from Earnshaw's theorem we get that we can't put a charge in a stable equilibrium with mere electrostatic forces, which is pretty logical as for being consistent with Laplace ...
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Thermal equilibrium analogy

If a glass of water at 100°C is placed in contact with a glass of water at 0°C, ignoring room temperature, the ideal temperature of water in both glasses would be 50°C, right? But since entropy causes ...
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How does an Anti-tilt chair work?

These chairs are designed as per European Educational Standard Part 1 and 2. These are claimed by the manufacturer as Anti tilt, so basically it makes it relatively difficult for a child to fall when ...
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Re-interpretation of the third law of thermodynamics

Consider the first paragraph of this paper: A fundamental problem in thermodynamic and statistical physics is to study the response of a system in thermal equilibrium to an outside perturbation....
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Zeroth law of thermodynamics confusion

I quote from Zemansky's "Heat & Thermodynamics"; "Imagine two systems A and B separated from each other by an adiabatic wall but each in contact with a third system C through diathermic walls, ...
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Why is that a system with a concave-up entropy-energy graph cannot have a stable thermal equilibrium?

This is from Schroeder's An Introduction to Thermal Physics: Let A and B be a system both with a concave-up entropy-energy graph. The systems will achieve thermal equilibrium when they are at the ...
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Minimum number of charges in an oscillatory system

I was just curious actually. Is it possible to release a set of point-sized charges in space, each particle at rest, such that after a period of time, the system returns to its initial ...
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Potential energy function term meaning [closed]

I can't seem to understand what this question is asking. I am not sure really what the second and third terms actually represent in the equation. Near the equilibrium position $r_0$, the ...