All Questions
Tagged with newtonian-gravity planets
311
questions
4
votes
4
answers
343
views
What is the relationship between gravitation, centripetal and centrifugal force on the Earth?
I'm trying to analyze a situation wherein a ship is moving across the surface of the earth. I am trying to analyze this situation in a reference frame that is rotating with the earth (NED frame).
I am ...
- 311
1
vote
2
answers
78
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The topology of planets [duplicate]
Just a curiosity:
Let $g \in \mathbb{Z}_{>0}$. Is it possible for a planet of topological genus $g$ to exist? For example, is there any contradiction (from the point of view of physics) in assuming ...
- 121
0
votes
2
answers
82
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Why are planets denser as you approach the center?
Gauss' law says that the net electric force inside a hollow, uniform, not rotating sphere is zero. Since gravity is also proportional to the inverse square of the distance, I assume this should apply ...
- 533
1
vote
4
answers
160
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Gravitational attraction between two bodies
While the gravitational force between two bodies is directly proportional to their masses, and inversely proportional to the distance between them is understandable / seems logical, how did Newton ...
- 123
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1
answer
21
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Can we treat the entire mass of the spheroid as being concentrated at its center?
I know that to find the gravitational force between two objects, if either of them is a sphere, we can assume its mass to be concentrated at its center and use the formula for gravitational forces for ...
- 69
0
votes
2
answers
65
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How symmetric do we know the gravitation field to be?
Currently, the only ways to measure gravity is on quite large scale. So these experiments measure gravity averaged between vast systems of particles. Of course, such an averaging results¹⁾ in a ...
- 101
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
1
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2
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98
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How to calculate equilibrium height of tidal bulge?
I am trying to model the shape of the tidal bulge caused by the moon.
I asked GPT for a formula and it gave me equilibrium tidal bulge height as
$$\frac{2 R_{earth} G M_{moon}}{3 r^3 \Delta g}$$
and ...
- 5,148
0
votes
4
answers
110
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What is the real shape of Earth? [duplicate]
As it now widely dicussed and accepted that Earth is not a 'perfectly round sphere/ball but more a 'oblate spheroid' why then do NASA have 'photographs' of a ROUND Earth?
- 11
4
votes
2
answers
326
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Exact analytical solution for the surface gravity of an oblate spheroid
I would like to know if an exact solution for the surface gravity force components of an oblate spheroid has been published and if not can anyone derive it here?
Assume an ideal rigid oblate sphere of ...
- 6,112
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answers
42
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Why is Earth a sphere? [duplicate]
Physicists and Physics enthusiasts . I am new to this platform. And I wanted to post a question . Since I have nothing in my mind. I wanted to ask , Why is the earth a sphere and not other shape?
...
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0
votes
1
answer
59
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What is the hydrostatic shape of an ideal rotating planet? [duplicate]
It is a well-known fact that rotating planets have a flattened spheroidal shape. However, the NASA site says about Haumea:
The fast spin distorts Haumea's shape, making this dwarf planet look like a ...
- 866
0
votes
0
answers
44
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Gravity formula inside a planetary core
I am trying to work through this problem so that I can understand how to convert from pressure values to radius values inside a planetary core in a code. The core has variable density depending on ...
0
votes
1
answer
61
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Issue while understanding gravity/radius of earth graph [closed]
I have following question.
What are my opinions?
1. Option 1 - This is incorrect. I think dotted line in option 1 from bottom to peak represents center to surface of earth. After the peak, line ...
- 85
-2
votes
1
answer
75
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Potential energy with different heights [duplicate]
If system consists of earth and ball and ball is dropped from height $h_i$ to $h_f$, then:
$\Delta U = -(W_{earth} + W_{ball})$ ($W_{ball}$ can be neglected since it's small)
$\Delta U = -(-mg(h_f - ...
- 1
0
votes
0
answers
69
views
Dynamic equilibrium of planets
We can describe statical equilibrium ( forces, moments ) in a cuboid $$ \Sigma F_x=0,\Sigma F_y=0,\Sigma F_z=0~$$ In dynamics can we describe similar dynamic equilibrium within an inertial ...
- 1,032
2
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1
answer
1k
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What does Newton's Theorem XXXIII in his book "Principia" mean?
If to the several points of a given sphere there tend equal centripetal forces decreasing in a duplicate ratio of the distances from the points; I say, that a corpuscle placed within the sphere is ...
- 870
8
votes
2
answers
795
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How would the volume of a drop of water (from a dropper) on the Moon and other bodies compare to one on Earth? (indoors of course!)
Searching for "volume of a drop of water from an eyedropper", I ran across this answer on Quora:
It depends on the size of the dispensing tip, but generally for a Pasteur pipette it is ...
- 6,273
8
votes
5
answers
290
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What is the gravity in the center of Earth?
Let's suppose the earth is a perfect sphere and let's ignore its rotation and movement.
What would happen if I would be in the center of the earth? Would the gravity be zero in any direction so I ...
- 209
1
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2
answers
47
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Is it possible to determine if a planet can have a moon based on its mass and gravitational pull?
I'm curious, if based on what we know with Newton's law, can we determine if a random planet, knowing it's mass and gravitational pull, can hold a moon in it's orbit.
Or to phrase it another way, is ...
- 111
0
votes
3
answers
345
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If the Earth rotated slower about its axis, would your apparent weight increase or decrease?
The title above was a question on an exam that was marked wrong for me. I answered that if the Earth rotated slower (i.e. longer days), my apparent weight would increase. I based this on the ...
- 135
2
votes
1
answer
69
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On the tidal heating of a moon. What is the second Love number?
Years ago it was asked here how to calculate the tidal heating of a moon orbiting another body with a simple equation. The answer is very detailed. They explain the equation, its shortcomings, the ...
2
votes
2
answers
356
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Is $F=mg$ derived from Newton's law of universal gravitation $F=Gm_1m_2/r^2$?
If so, that means gravity is only 9.8 m/s^2 at the surface of the earth?
- 21
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votes
1
answer
92
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Change in $g$ effective due to rotation
$g$ effective at any latitude changes due to rotation of earth. Does it also change due to rotation when the body is at height or at depth or does it change only at the surface?
Edit: I am referring ...
- 69
1
vote
2
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377
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Correct explanation of tides [duplicate]
In the explanation of tides on earth there seem to be different versions for the second water bulge on the side opposite to the moon, while everybody seems to agree that the bulge on the moon side is ...
- 4,292
14
votes
9
answers
7k
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Is Earth really flattened at the poles because of centrifugal force?
My question is pretty much all in the title. I was always told that our planet is flattened at its poles due to the centrifugal force generated by its own rotation. However I don’t see how centrifugal ...
- 427
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1
answer
78
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How does a gas giant planet hold it's spherical shape when it has tidally locked rotation in it's orbit around the Sun?
How does a gas giant planet hold its spherical shape when it has a tidally locked rotation in its orbit around its Sun? Wouldn't it fall apart without its gravitational pull from the rotation? How ...
6
votes
2
answers
2k
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Possible non-negligible physical effects that relate planetary/lunar geometry and seismic activity such as earthquakes?
Could any forces from the moon, the planets or the sun in orbit hypothetically influence seismic events on earth? And if yes how to approximately calculate and compare the magnitude of the forces?
...
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2
votes
1
answer
77
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Falling at the centre of the Earth
Let’s assume to drill a hole at Earth surface at the point P1. The hole passes throughout the centre of the Earth and finishes at the opposite side at the point P2. Let’s assume then that 1) Earth ...
- 566
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0
answers
41
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Did Newton derive Titius-Bode Law of the planets in his Principia? [closed]
In college I was taught that no one knows why the planetary orbits conform to the Titius-Bode Law.
Recently I read that Newton HAD figured that out in his Principia.
Right Now I can’t even find a ...
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