Covers the study of (mostly homogeneous) macroscopic systems from a heat/energy/entropy point of view. Maybe combine with [tag:statistical-mechanics].

learn more… | top users | synonyms (2)

0
votes
0answers
6 views

Why nitrogen cannot be sealed in closed container?

By observing the phase diagram of nitrogen, hydrogen and carbon dioxide, I discovered the supercritical region. I can easily buy a gas tank of carbon dioxide at 250 Bars. However I never saw any ...
0
votes
0answers
9 views

Why can only asymptotically flat and Ads black hole have the thermodynamics? What's about asymptoticaly ds blackhole?

Almost all advanced GR textbooks will have the content of black hole thermodynamics for asymptotically flat black hole. And this paper solve the asymptotically Ads(Anti-de Sitter) black hole ...
1
vote
0answers
23 views

Heating soil by 1C and maintain the temperature

I would like to calculate how much energy I would need to heat soil by 1C for, let's say, a month. So far, my findings are as follows: First of all let me say I could not attach all the reference ...
-1
votes
1answer
34 views

Boiling water function

i want to make a program that realistically boils water with all the variables but know near nothing about the math i got the energy transfer equation down but this seems to be giving me some ...
-1
votes
0answers
25 views

13 watt coffee cup warmer and fish tank? [on hold]

I have a small fish that I wanted to keep warm and seperated from his larger fish tank. I have a large glass measuring cup in which I'll place water. (Up to 500 ml) My room temperature is 75 degrees ...
0
votes
1answer
25 views

Is average kinetic energy equal to the total thermal energy of a gas?

"Average KE" as in this equation: $$K_{average} = \frac{3}{2} kT$$ Since potential energy in ideal gas model is eliminated, I guess this equation is also for the total thermal energy of a gas/a ...
3
votes
3answers
82 views

Does wax go through a sharp phase transition when it melts?

When ice melts, the system goes sharply from being solid to being liquid. There is no intermediate state where it is soft. This is a true phase transition. The thermodynamic potential is not an ...
0
votes
3answers
42 views

How is Work by a System Interpretated in the First Law?

Good evening. I've happened to be sitting down today and just couldn't wrap my head around this question which seems rather simple at first. From reading about the first law and sign conventions as it ...
1
vote
3answers
55 views

Zeroth law of thermodynamics and related discrepancy?

Consider the case: Assume molecules to sphere and their |velocity| as an indication of their temperature. Now for head on elastic collision (i.e transfer of heat), assume the momentum is conserved ...
0
votes
0answers
19 views

What allows some objects to have a high specific heat capacity?

I know that temperature is a measure of thermal energy associated with the KE of molecules. But when heat enters an object, surely those molecules now start vibrating and translating, so this results ...
-1
votes
0answers
22 views

Basic Thermodynamics: Adiabatic Process

we know that for adiabatic process $W=-\nabla E$. My question is here why do we consider $W=nC_v\nabla T$
0
votes
0answers
39 views

Efficiency of a compressed air engine

I am doing some personal research on the efficiency of compressed air cars. I am currently trying to come up with an 'ideal' cycle to use as a reference for efficiency (c.f. Otto Cycle for petrol ...
0
votes
1answer
23 views

Accounting for the thermal excitation in the Richardson-Dushmann equation or the work function equation

When accounting for thermal excitation in a system that is not in thermal equilibrium, heat is constantly flowing through a material, should I account for the thermal excitation in the work function ...
0
votes
1answer
63 views

Is there a formula/relationship between $q$, $m$, $c$, $\Delta T$ and $t$ (time)?

I am currently doing an experiment where I am burning methanol to test for the heat of combustion. To test this, I am heating 100g of water and raising it by 20 degrees Celsius before extinguishing ...
1
vote
1answer
36 views

What causes a eutectic point?

What causes the melting point depression known as a eutectic point? The temperature depression of a eutectic point can be calculated from the enthaplies and entropies of fusion of the two ...
1
vote
2answers
49 views

What is the perfect Ice Cube? [closed]

I have a freezer with -25°C temperature and Soda with +30°C. What is the ice-cube-sized material I can put in the freezer that can bring my glas of soda to the lowest temperature? Are e.g. saltwater ...
1
vote
0answers
28 views

Expression of heat by the Brownian motion

folks. I was reading a paper from PRE and I'm not sure what's going on about the following equation. So for the system composed of two heat baths governed by Brownian motion, the entropy change of the ...
-2
votes
0answers
26 views

Finding root mean square speed of an ideal gas [closed]

Again a question ive never seen in my life... The molecules of an ideal gas have a root mean square speed of 520 meters per second at a temperature of 27 degrees celcius. Calculate the r.m.s speed ...
4
votes
1answer
154 views

Does an ice cube change its core temperature as it melts?

Let's say we have an ice water solution in an ambience with room temperature, i.e. there is a permanent exchange of energy. Let's suppose the ice cubes were from the freezer, which is at $-18°C$. The ...
-1
votes
1answer
90 views

Why is not the entropy of earth increasing? [closed]

The entropy of earth is not increasing significantly in the past billions of years. So what is the reason? It must be because of the sunshine. But I still do not have a concrete picture.
-3
votes
0answers
119 views

Doping in physics [closed]

compare and contrast the principle involved in doping and bonding. Why do increase in thermal agitation in semiconductor result in increase in conductivity
-2
votes
0answers
26 views

thermodynamics question [closed]

I've thought this question for a really long time and now i need help..... The question is "the volume occupied by a mole of liquid water at 100 degrees celcius is (1.87 exponent -5) cubic metres. ...
-4
votes
1answer
40 views

Alka Seltzer Model: formulas/models requested [closed]

This evening I became fascinated with how my Alka Seltzer tablet disintegrates over time within a small portion of Diet Lipton Citrus Ice Tea. I used a nearly frozen cup; tall, as one might request in ...
1
vote
5answers
85 views

What happens to the kinetic energy of a dropped ball when it comes to rest on the ground?

If we want to drop a ball from a height, we calculated that potential energy at bottom is zero and we say it is converted into kinetic energy. At that movement, if it is a kind of sand, we find it ...
1
vote
0answers
33 views

Why do particles in a medium have different speeds?

If thermal conduction occurs because of particles colliding with each other and imparting kinetic energy to each other, won’t the particles of an isolated medium collide with each other until the ...
-1
votes
1answer
29 views

Is there anything that can be heated with least electricity? [closed]

Do you know any element or product that can attain around 400 Celsius of temperature with the least requirement of electricity. I've been looking at the heating coils but most of them are rated as ...
1
vote
3answers
90 views

Can a Dyson Sphere around a Black Hole be built so that it would not radiate significant IR?

This is related to this question If the sphere surrounded a BH and used it as a heat dump (as well as extracting energy from it by dropping in mass) could its exterior be engineered to match the ...
-1
votes
1answer
46 views

How long will pressure exist in this case?

I'm currently fabricating my project, which currently exists only on paper, and there's one question to which I have stumbled today. Suppose, that I have a pressure vessel capable of holding upto ...
16
votes
2answers
2k views

Do chemical bonds have mass?

When an exothermic reaction occurs, the energy in the chemical bonds of the reactants is partially transferred to the chemical bonds of the products. The remaining energy is released as heat. For ...
0
votes
2answers
42 views

Understanding speed distributions: Average speed, RMS speed from a graph?

So taking a look at this graph.... ![http://i.imgur.com/XUwpnSK.png][1] I want to express $A$ in terms of $N$ (total # of particles) and $V_0$. So I've found the piecewise function for $f(v)$ and ...
0
votes
0answers
24 views

bose einstein phase transition

From Carter's book Thermodynamics and Statistical Mechanics, the partition function of a bose-einstein gas in $d$ dimensions is $$ \ln(Z) = ...
0
votes
0answers
10 views

Adding thin films to a Peltier Device

I am using a peltier device maintaining a constant gradient by applying a voltage/current. My current setup is: Cold Side Peltier Device Hot Side CPU fan Was just wondering forgetting time ...
0
votes
3answers
57 views

Does a gas in a container lose kinetic energy?

When a gas is in a container, it frequently collides with the container wall, exerting pressure. However, with a collision, kinetic energy ought to be transferred from the gas molecule to the ...
2
votes
0answers
49 views

Does second law of thermodynamics imply the big bang?

Given that the second law of thermodynamics states that entropy always increases and the universe is currently not in a state of maximal entropy does that not imply that it must have started at a ...
0
votes
0answers
19 views

Making Pudding; A complicated non-equilibrium statistical process?

There are a lot of non-equilibrium processes examples given in physics literature. But some processes that are present in everyday life are not treated. As an example, the formation of pudding can be ...
0
votes
0answers
22 views

Heat engine with three thermal baths

I was wondering if we can surpass the efficiency of the Carnot engine with three thermal baths, so my question is: Is the most efficient heat engine among three temperature reservoirs a cycle ...
2
votes
0answers
26 views

Car Heating due to the sun: comparison of different contributions

Let's imagine that we need to choose a car in order to minimize the Temperature that the inner part of the car will reach after some hours under the sun. We know that two factors (if we suppose that ...
2
votes
0answers
53 views

How to calculate the energy in thermoelastic damping?

Note - I'm not 100% sure *thermoelastic damping* is the right term here - so please feel free to correct the question in case I'm wrong! If a force is applied to an elastic rod such that it ...
0
votes
1answer
21 views

Temperature and Heat question [closed]

So I have a problem about calculating the specific heat of a metal. I'm using the philosophy "Heat gained = Heat lost". The problem is: When 50g of a metal at 280C is put into a calorimeter ...
1
vote
3answers
150 views

How can space be cold? Its a vacuum? [duplicate]

I was reading that space is very cold and also it is a vacuum, and so my question is quite simple, if temperature is the "jiggling" of atoms and molecules and heat is distributed through jiggling ...
0
votes
1answer
39 views

Heat transference in my lunch [closed]

Say that I have a hot sandwich and a cool salad, both in functionally-identical plastic containers that provide no effective heat insulation. I need to stack these two containers for ease of ...
1
vote
0answers
43 views

Thermodynamics with explicit math

Nathaniel adeptly answers a question on thermodynamics by making the variable dependencies explicit: Determine the Dependence of S (Entropy) on V and T Is there a thermodynamics text that is written ...
0
votes
3answers
61 views

About energy… created, destroyed?:/

Consider a dam, in that first the hydraulic energy due to gravitational force gets converted into mechanical energy by using turbine. Then those mechanical energy is converted into electrical energy ...
1
vote
1answer
80 views

canonical ensemble that is quantum mechanical and continuous?

I do not understand what the following statements from Wikipedia mean For a canonical ensemble that is quantum mechanical and continuous, the canonical partition function is defined as $$ Z = ...
1
vote
0answers
26 views

How does fluid velocity affect the dissolution of some solute in the fluid?

Suppose we have a perfect sphere of some solute such as sugar and we place it in a fluid such as water, at a certain temperature, that is not moving. It will dissolve and diffuse into the water due to ...
22
votes
4answers
5k views

How is it possible that it can get hotter in the car than it is outside?

The Law of Thermodynamics says that two bodies will eventually have equal temperatures. How is it possible that when you leave your car in the sun, it gets hotter in the car than it is outside? Why ...
0
votes
1answer
22 views

Effect on pressure for a decrease in temperature with respect to height

If I were to have a decrease in temperature with height, $T = f(z)$, I was wondering if I could calculate the pressure like so: Could I simply combine $$ \frac{dP}{dz} = -\rho g, $$ with the ideal ...
1
vote
1answer
38 views

Single story, hotter outside, some shade from porch, enough to cool house with/without air flowing?

So, I know this question, without shade or one-story, has been answered many times on the 'net, so I have some actual physics for the one-story. I am fairly certain my roommate mixed up thermal ...
0
votes
0answers
21 views

What happens when heating water in a pressure vessel?

Suppose that I take a pressure vessel that can hold up to 2000PSI force. Now I fill it with water (not completely, but around ~90%) and now I start to heat it with direct flame, LPG gas cylinder. What ...
0
votes
0answers
25 views

Theoretical efficiency Diesel vs Otto

The efficiency for the otto cycle is defined as: equation 1: $$ n_{otto} = 1 - \frac{T_4-T_1}{T_3-T_2} $$ which can be expressed in terms of the compression ratio: equation 2:$$ n_{otto} = 1 - ...