# Questions tagged [equilibrium]

Equilibrium is the condition of a system in which all competing influences are balanced. These can range from forces (static/dynamic equilibrium), to chemical processes (chemical equilibrium) and temperature gradients (thermal equilibrium).

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### Doubts about direction of normal contact force acting on a tilted rod supported by another body

I'm confused about the direction of the normal contact force acting on a body supported by another body. I have read the following : If a body is being supported by a surface, the normal force acting ...
345 views

### Equilibrium of a system of charges

Suppose three positively charged particles are constrained to move on a fixed circular track. If the charges were all equal, an equilibrium arrangement would obviously be a symmetrical one with the ...
1 vote
576 views

### Pressure of a system at the thermodynamic equilibrium

I'm reading a book in which it says that a system is at mechanical equilibrium if the pressure is constant in time but not necessarily uniform in space at any fixed point (for example it can be caused ...
57 views

### Torque equilibrium problem

We have a stick which is connected to the wall with a rope, like shown in the picture. I need to set the resulting torque to $0$, since it's in equilibrium. The solution in the textbook says: Pick a ...
1 vote
21 views

### Statics and torque equilibrium problem [closed]

This is a ladder, which is connected to a wall with a string (at the bottom - F is the tension in the string). It is in equilibrium at 60 degrees. I understand that I have to set the result of the ...
162 views

### Entropy and equilibrium concepts at astronomic scales

I am always puzzled to read here and there discussions dealing with thermodynamic concepts applied to astronomic scales where gravity matters. To my opinion, there is a certain carelessness to go into ...
62 views

### For what kind of thermodynamic systems are phase diagrams valid?

I understand that thermodynamic systems can be broadly categorized as open, closed or isolated. Do 2-D pressure vs. temperature type of phase diagrams apply to all three? Additionally, for closed and ...
274 views

### Thermodynamic equilibrium state of constant $(p,S)$ system

The internal energy as a function of its natural variables is: $$dU=-p dV+TdS$$ where $p$ is the system pressure and $dS$ includes only changes of the entropy due to heat transfer (the "...
111 views

### Can two particles ever be in equilibrium under their mutual gravitational forces alone?

Can two particles be in equilibrium under the influence of their mutual gravitational forces alone? Obviously, if the two particles are kept at rest at a distance apart, one will exert an attractive ...
75 views

### What regulates the size of our atmosphere?

Our atmosphere is only about 100km thick before the official start of space. That is a mere 1.57307% of the radius of Earth (6,357km). The difference between the gratitational force at sea level and ...
1 vote
392 views

### Why do we say that at boiling point liquid and vapour exist in equilibrium?

I understand that at boiling point, vapour pressure becomes equal to the external pressure. But in my textbook it is written that at boiling point liquid and vapour exist in equilibrium. What does it ...
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### What are some good articles on trend to equilibrium?

I am interested in studying systems out of equilibrium that are trending to equilibrium. Trend to equilibrium, entropy production, etc. seem to be very tricky topics. Any suggestions will be ...
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### A paradox while explaining the equilibrium of books

An even number of books (say four) are held in the manner shown in the figure. It is obvious that if we apply a large force inwards, we can increase the normal force, and hence the friction which ...