All Questions
Tagged with newtonian-gravity thermodynamics
43
questions
6
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6
answers
3k
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Why is pressure in the outermost layer of a star lower than at its center?
I have done the math and I have obtained the hydrostatic pressure in a star is lower at the outermost layer of a star than in its center, where the pressure is actually maximum. Although the equations ...
- 1,616
5
votes
2
answers
289
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Helium in Uranus atmosphere
I read that in 1986 Voyager 2 measured the composition of Uranus' atmosphere, which turned out to be composed of $85 \%$ hydrogen and $15 \%$ helium.
It's not clear to me how this relevant amount of ...
- 566
0
votes
0
answers
16
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Surface Tension vs. Gravity: Finding the Critical Length Scale
I'm studying Kardar's "Statistical mechanics of particles" book and tackled a problem. After solving it, I checked Kardar's solution and found that he has different approach. I'm interested ...
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votes
3
answers
76
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Does work done by gravity (alone) heat things up?
If we take the first law of thermodynamics:
$$ΔQ = ΔU+ΔW$$
And we consider a system of a ball falling from height $h$ in an Earth-like gravitational field(no air drag and $h$<<$Rₑ$)
$$ΔU = mgh$$ ...
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1
vote
0
answers
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Would a candle in very high gravity blow itself out?
A candle creates an upward draft of hot air, without which the flame would be spherical. The buoyancy generated is proportional to the density difference as well as the strength of gravity.
Suppose a ...
- 6,531
0
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1
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Amount of extension of the metal rods in the same system
If we heated two identical metal rod both vertically and horizontally, we would observe that it expands. However, if the rod is placed vertically, gravity will indeed play a role. The expansion of the ...
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2
votes
1
answer
94
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How long does it take for gas to settle down under earth's gravity?
I was discussing about ideal gas with my colleague the other day, and these questions come up in our conversation.
Lets say we have 1 mole ideal gas in a perfectly insulating cube box of size $1m^3$,...
- 170
-1
votes
1
answer
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How to add Newton's constant to the metric function?
My main question is, is it possible to manually add Newton's constant $G$ to the metric function of a black hole? Is there such a possibility for Black Brane? How to add? Should it be added to the ...
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1
vote
1
answer
94
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Temperature of a particle moving in a gravity field
I have a seemingly simple question that is still puzzling to me.
The temperature of an atom is proportional to its kinetic energy. If an atom now moves upwards in a gravity field, its kinetic energy ...
- 193
2
votes
2
answers
310
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Is osmosis stronger or weaker than gravity, and by how much?
Suppose you perpare a jar of salt water and another of sugar water and invert one on top of the other with a divider between them, and then carefully remove that divider so the liquids are in contact.
...
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0
votes
1
answer
57
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Gravity train in other planets?
A Gravity train (https://en.wikipedia.org/wiki/Gravity_train) goes through a tunnel inside a planet that connects point A with point B. On Earth, the train would not gain enough impulse to reach the ...
- 2,462
0
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2
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100
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Could gravity be used to cool down matter?
Thermal energy being the movements of particles, could we have a system that could use gravity to reduce the thermal energy of particles?
For example, if we imagine:
A box containing Argon in its ...
- 101
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votes
1
answer
46
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When a star loses temperature its matter loses KE so does it mean the star's gravity weaken?
When a star loses temperature its matter loses KE so does it mean the star's gravity weaken? The question is based on Einstein's field equation which states that energy also contributes in space-time ...
- 1,815
1
vote
2
answers
484
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How does gravitational potential energy pertain to a single gas particle escaping the atmosphere?
What's the effective difference between a helium molecule moving at 11.18 km/s and one moving at 11.2 km/s at the edge of the atmosphere? Is the idea that, with a particle moving just below the ...
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9
votes
7
answers
14k
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What is gravity's relationship with atmospheric pressure?
I'm asking for clarification here. If Earth had the same atmospheric mass per square unit of ground but the Earth had suddenly gained mass so it had twice the gravity at the surface, would the Earth ...
- 227
2
votes
5
answers
656
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The question of the second law of thermodynamics [duplicate]
I am asking question which definitely will be considered as duplicated but I want to ask it more explicitly to prevent empty speech.
Suppose we have "closed" system which is consists of ...
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1
vote
0
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76
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Is a planet hot inside because it is still hot from beginning, or continuously heated? [duplicate]
If a planet emerges from multiple colliding pieces, that causes its material heat up.
Later, an existing planet is continuously heated by radioactive decay, tidal forces and other effects.
But are ...
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1
vote
1
answer
231
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How does the Earth have enough gravity to hold on to its atmosphere? [duplicate]
I'm looking for numbers/math that describe how earth (or any other planet) holds on to it's atmosphere.
Presumably, we would be able to determine the exact atmospheric pressure that we would expect ...
- 11
1
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3
answers
373
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What will happen if we boil water in the absence of gravity?
We know that, Convection is the mode of heat transfer due to the motion of individual molecules of a fluid (liquid or gas). The motion of the constituent particles arises due to difference in ...
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56
votes
3
answers
15k
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How does the Earth's center produce heat?
In my understanding, the center of the Earth is hot because of the weight of the its own matter being crushed in on itself because of gravity. We can use water to collect this heat from the Earth and ...
- 682
4
votes
1
answer
79
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What would happen if we had a crystal structure but only gravitational interactions?
The idea is simple. Let's say we arrange similar bodies (call them planets, ions, anything) in an infinite crystal structure, but the only possible interactions are gravitational interactions.
A ...
- 165
2
votes
2
answers
545
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Energy of room. Ideal gas law
I have been following Blundel's "Concepts of thermal Physics" and I got to the derivation of the ideal gas law. And it all made sense, we made a couple of assumptions and approximations, but then I ...
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2
votes
1
answer
57
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If a galaxy forms from a spherical stationary cloud, how much of the gas will escape?
Let's ignore the dark matter legend and stay with Keplerian physics.
Assuming that there is a cloud with $N$ stationary particles with the same size uniformly distributed in a sphere and they ...
- 21
1
vote
1
answer
135
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Champagne bubbles and gravity
One of the influences on bubble size is the speed with which a bubble rises in a glass - this, I believe, is due to the force of gravity which acts on the liquid around the CO2. The greater the ...
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2
answers
258
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Weight of a container of gas and container shape [duplicate]
Consider a cube shaped container with one mole of gas inside.
Acceleration due to gravity would give the difference in force between the top of the container and the bottom to be mg, with net force ...
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22
votes
2
answers
3k
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Can someone explain this Freeman Dyson quote about gravity and thermodynamics?
I was reading a book review by Freeman Dyson at http://www.nybooks.com/articles/2018/05/10/the-key-to-everything/ and he makes the following statement at the end of the 13th paragraph (3rd dropcap) ...
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1
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4k
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Vertical surface would lose heat faster by convection than a horizontal surface?
Is the heat coeff affected by gravity?
Vertical surface would lose heat faster by convection than a horizontal surface?
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votes
3
answers
584
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Entropy and gravitational attraction
Any process which is spontaneous and irreversible must involve a (positive) change in entropy of the universe
This is one condition to the spontaneity of a process that the overall universe (System + ...
- 1,059
48
votes
9
answers
21k
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Why is air not sucked off the Earth?
People said outside earth is a vacuum. But the air does not get sucked from the Earth's surface. Some said it is due to gravity and some said the speed of air molecules are not high enough to escape....
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1
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145
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How come the Earth is not crumbling into the core due to fact that the core is in the middle of it? [duplicate]
I always wondered why isn't the Earth shrinking or melting because of the core.
- 414
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2
answers
202
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Global warming: change in Earth's potential energy
It is quite common to hear in newspapers and television about the increasing temperature, i.e. global warming.
But I am interested in something else.
How does global warming affect the internal ...
- 347
0
votes
3
answers
2k
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What is precisely the reason that a helium balloon ascends?
A simple question with no clear answer for me: Helium is lighter than air and lighter air rises. That's it!?
I) A helium atom is approx. 4 times as light as an an air molecule. With 4 times less mass ...
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9
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5
answers
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How does hot air act in zero gravity?
In an environment with gravity, hot air is less dense than cool air, so it rises.
How does hot air interact with cold air in a zero gravity environment, in terms of movement? Does it just stay where ...
- 191
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4
answers
2k
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Does gravity acting on a resting object produce any heat?
Let's compare two systems.
System 1: A box is completely isolated. There are no forces acting on that object, and no interactions of any kind with other objects, waves, etc..
System 2: The same box ...
- 556
12
votes
2
answers
794
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Will Neil Armstrong's moon boot marks really last for thousands of years?
This question concerns the residual heat (if any) contained within the Earth's moon.
At the time of the Apollo moon landings, it was widely reported that the boot marks left by the astronauts would ...
user81619
5
votes
1
answer
202
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For $N$ particles acting under gravity, how long until they settle into a virial equilibrium?
As the title says, if I have a system of particles interacting only due to gravity, over what timescale do we expect them to fall into a virial equilibrium?
By virial equilibrium I mean a system that ...
- 1,751
15
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3
answers
3k
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Which ball falls faster, the cool one or the hot one?
Suppose we're on the top of the Tower of Pisa (or a larger version of it) with two identical cannonballs. We heat one up (say, to 200 degrees Celsius, or some other high temperature before it starts ...
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vote
2
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Heating of two identical balls [closed]
You are given two identical steel balls of radius (say) 5 cm. One ball is resting on a table, the other ball is hanging from a string. Both balls are heated (with a blow torch) until their radii have ...
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32
votes
11
answers
5k
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In reverse time, do objects at rest fall upwards?
I want to develop a game where time runs backwards, based on the idea that physical laws are reversible in time. However, when I have objects at rest on the earth, having gravity run backwards would ...
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3
answers
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How does one calculate where the "surface" of a gas-giant would be?
Okay, so Jupiter, Saturn, et. al are gas giants. I understand that they have large gassy atmospheres, which, due to the pressure would eventually become more and more dense as one approaches the ...
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votes
3
answers
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Does gas spread out equally everywhere?
An excerpt from this page:
Gases can fill a container of any size or shape. It doesn't even matter how big the container is. The molecules still spread out to fill the whole space equally. That is ...
- 1,531
6
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3
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What keeps a gas giant from falling in on itself?
There is not enough gravity at the center to start nuclear fusion, but it seems that there would be plenty enough to collapse the planet.
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6
answers
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Can low-gravity planets sustain a breathable atmosphere?
If astronauts could deliver a large quantity of breathable air to somewhere with lower gravity, such as Earth's moon, would the air form an atmosphere, or would it float away and disappear? Is there a ...
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