Thermodynamical potentials: some hand-waving please

  • Thread starter Thread starter jonas_nilsson
  • Start date Start date
  • Tags Tags
    Potentials
AI Thread Summary
The discussion centers on the understanding of thermodynamical potentials in the context of statistical physics. Participants express a desire to develop an intuitive grasp of what these potentials represent and how they relate to thermodynamic principles. The conversation highlights the importance of recognizing the roles of internal energy, enthalpy, and Gibbs free energy in physical processes. An analogy involving conjuring a rabbit illustrates the need to consider molecular assembly, work done, and energy extraction. Overall, the aim is to bridge theoretical concepts with practical understanding in thermodynamics.
jonas_nilsson
Messages
28
Reaction score
0
Hello!

I am right now occupied with statistical physics, and of course the connections to thermodynamics are always there. We are especially verifying the old-school thermodynamical results. This leads to a lot of talking about thermodynamical potentials, but I feel that I and most of the students lack a "feeling" for them.

I would appreciate if some people could do some hand-waving and tell me what "feeling" they have developed for the thermodynamical potentials. What do they really describe? I'm sure it would help us out also with the theoretical stuff.


Jonas
 
Physics news on Phys.org
Suppose you wanted to conjure a rabbit in your hat. For one thing, you would have to assemble the molecules:

dU=\mu dN

But you would also have to do the work to make room for the rabbit:

dU = \mu dN + P dV (Enthalpy)

And you can extract some energy from the surrounding air to help you:

dU = \mu dN + P dV - T ds (Gibbs free energy)
 

Thread '1:1 versus 2:1 Mechanical Advantage debate'

The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
View full post »

Thread 'Newton's first law?'

Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
View full post »

Thread 'Free fall of person in a sled to direct horizontal motion by atmospheric resistance'

Let there be a person in a not yet optimally designed sled at h meters in height. Let this sled free fall but user can steer by tilting their body weight in the sled or by optimal sled shape design point it in some horizontal direction where it is wanted to go - in any horizontal direction but once picked fixed. How to calculate horizontal distance d achievable as function of height h. Thus what is f(h) = d. Put another way, imagine a helicopter rises to a height h, but then shuts off all...
View full post »

Similar threads

I Relationship between nuclear magnetic physics and Maxwell's demon
Replies
1
Views
123
I How to interpret this definition of potential energy?
Replies
10
Views
2K
Classical Looking for a thermodynamics book that 'ties it all together'
Replies
10
Views
4K
I Drag Coefficient of a 'flexible' object (e.g. a piece of paper)
Replies
4
Views
2K
Longitudinal waves and vector potentials.
Replies
3
Views
2K
A Wave Function Collapse and Thermodynamic Irreversible Processes
Replies
4
Views
2K
Courses Class ordering for next upcoming semesters
Replies
21
Views
2K
Studying Should I first study the math or math and physics at the same time?
Replies
9
Views
4K
I Galaxy redshift and thermodynamics
Replies
10
Views
3K
Engineering To engineers: do you often read texts intended for physics majors?
Replies
5
Views
2K

Hot Threads

Recent Insights

Back
Top