All Questions
Tagged with newtonian-gravity thermodynamics
43
questions
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 ...
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48
votes
9
answers
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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....
- 609
32
votes
11
answers
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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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22
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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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15
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3
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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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14
votes
6
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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 ...
- 477
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
10
votes
3
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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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9
votes
7
answers
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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
9
votes
5
answers
3k
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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 ...
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8
votes
3
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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
6
votes
6
answers
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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 ...
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6
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3
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2k
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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
votes
3
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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
5
votes
2
answers
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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 ...
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