All Questions
87
questions
-6
votes
1
answer
52
views
Why sun revolve around the sun ? Why cant it just rotate ? ( gravitas attraction force makes it revolve , how?) [closed]
Why the revolution ?
How General relativity theory explains it
1
vote
3
answers
87
views
The speed of an impulse transmitted along a string
A supernova explosion on the far side of the Sun ejects a mass with approximately the same mass of the Sun directly at the back side of the Sun. If this ejected mass is travelling arbitrarily close to ...
0
votes
2
answers
93
views
What earthbound experiments show gravitation is general to all matter, and not just towards the earth?
I was debating a flat earther and predictably it turned into a debate on gravitation. He said as far as we know, things fall down to the earth, not because its towards the greatest mass. The ...
- 1,821
0
votes
1
answer
42
views
Distribution of Earth's mass and its role in the nodal precession of satellites?
From what I have read and understood so far, the nodal precession of a satellite in low Earth orbit is caused by the bulge equatorial of the Earth (caused by its rotation on itself) which moves the ...
1
vote
0
answers
65
views
The radius of Earth is 4 times the radius of the moon. Estimate the acceleration due to gravity on the surface of the moon [closed]
I have derived an expression here which just needs the ratio of the densities of the Earth and its moon. My question is how do I go about finding this ratio or is there another way to approach this ...
0
votes
1
answer
45
views
Would obliquity and precessional changes of Earth affect the accuracy of GPS-based measurement of tectonic movements?
The rate and direction of tectonic movements can be measured by comparing the coordinates of the same GPS receiver over time. The coordinates are obtained using trilateration.
All materials I could ...
- 81
0
votes
3
answers
1k
views
Why is it said that gravity is weaker at the equator due to centrifugal force? [duplicate]
Gravity would only be weaker at the equator if mass is not the only thing that produces gravity or if there is dense enough matter near, or at, the center to offset the additional volume of mass that ...
- 1
1
vote
1
answer
112
views
Why does $g$ vary from a direct square relationship inside the earth to an inverse square relationship above the earth's surface?
Why does acceleration due to gravity $g$ vary with altitude, height, and depth from a direct square relationship inside the earth (below the earth's surface) to an inverse square relationship above ...
user324347
1
vote
2
answers
266
views
Lag in Direction of Earth-Sun Gravity vector
When the earth is orbiting around the sun, it experiences a force vector pulling it towards the sun, which acts as a centripetal force for its elliptical orbit. However, when the earth moves a bit ...
- 111
2
votes
1
answer
110
views
Which location on Earth has the strongest deviation from the vertical due to gravity?
So, I've recently learned about the Schiehallion experiment, performed in 1774, where scientists detected the deviation from the vertical of a plumb due to the gravitational attraction of a single ...
- 2,987
0
votes
1
answer
202
views
Can anyone explain how does an object move upward from the surface of the earth defying the spacetime curvature?
I am trying to understand the while concept of spacetime curvature. Space is a fabric which is bent by heavy masses. But I don't understand that why objects follow the geodesics and get attracted to ...
0
votes
1
answer
41
views
When the Earth suddenly stops pulling [closed]
Let's say the Earth stops attracting objects to itself all of a sudden. So, I was wondering what would happen to a person standing on the surface of the Earth? (Neglect the effect of the rotation of ...
10
votes
9
answers
4k
views
Why and when can the Earth be considered an inertial reference frame?
The question has been asked (e.g., here and here), but I would like to get a more definitive and mathematically formal answer.
The Earth rotates around its axis, around the Sun, and participates in ...
- 60.3k
0
votes
0
answers
47
views
If the Earth is constantly accelerating at 9.8m/s^2, according to General Relativity, won't Earth's speed be constantly increasing towards infinity? [duplicate]
As per Einstein's Theory of General Relativity, I understand that 'the Earth's ground is accelerating towards us at 9.8m/s^2. This is why we're falling towards the center of the Earth, as GR doesn't ...
5
votes
5
answers
1k
views
Gravity is not a force - how does "accelerating up" work for the entire earth? [duplicate]
So this question has been bothering me for several days now. I've seen many YouTube videos on how "Gravity is not a Force", but no one seems to offer a simple explanation on how does this &...
- 183
0
votes
0
answers
38
views
Does anyone know where I can find values of gravity?
Does anyone know where I can find the values of gravity at different places across the globe and at different heights? I am doing an assessment on gravity and can't find any data for the values of ...
1
vote
0
answers
41
views
Atmospheres and oceans on lower gravity planets
Using Earth as an example, how much less gravity could the planet exert and still retain its atmosphere and oceans? Or is it a matter of size, mass, magnetosphere, place in the solar system, all of ...
- 111
0
votes
2
answers
501
views
Do magnetic things fall faster?
Assuming correct orientation, do magnetic things fall faster than non-magnetic ones because of the magnetic field of the Earth? Of course it is clear that if any, the effect is very very small, but ...
- 101
0
votes
2
answers
171
views
Would a body have any residual velocity if launched at escape velocity from the Earth's surface?
A body is lanuched at escape velocity from the Earth's surface i.e 11.2 km/s ,what would be it's velocity outside the Earth's gravitational field?
I guess it would be zero but there's another problem ...
- 41
1
vote
1
answer
177
views
Can centrifugal force inside Earth's outer core overcome gravity?
As the gravitational field inside Earth outer core is relatively weak can the angular momentum of Earth's outer core be high enough to cause lighter elements or compounds being deposited in Earth's ...
- 2,255
8
votes
7
answers
10k
views
Why doesn't Einstein's general theory of relativity seem to work on Earth?
I am new to physics and I have learned a little bit about gravity from Einstein's perspective. The gist is that heavy objects create curvature of spacetime, and free-falling objects move on the ...
- 253
0
votes
3
answers
123
views
Is it possible for meteors and asteriods to become natural satellites of Earth?
We know that the moon isn't falling on the earth because it's in orbit. If we make an asteriod or meteor spin is it possible for it to become a natural satellite of Earth?
- 555
0
votes
0
answers
73
views
Is Earth flat according to Einstein? [duplicate]
I didnt understand how to apply general relativity to Earth. If there is no such a thing as gravity but spacetime bending. Can someone just show, send something to read how gravity works in Earth ...
- 11
-1
votes
1
answer
178
views
Gravitational field of sun [closed]
Let there be a solar system without Earth.
Now what happen if we place the Earth suddenly on its actual position does the gravitational force of sun acts on it immediately because of its pre ...
- 335
0
votes
2
answers
530
views
In the tunnel through the Earth thought experiment, how does total energy of a particle vary when it goes from surface of the Earth to its center?
In the typical tunnel through the center of the Earth thought experiment, a particle at the surface would oscillate between the two diametrically opposite points ignoring the rotation of the Earth. ...
- 3
0
votes
1
answer
690
views
What would happen to the water bodies if gravity ceased to exist on Earth?
If water stopped flowing (it would stop flowing downwards from mountains and all)
then, would it start rising upwards? If it floats on the space ( I say space because there'd not be any atmosphere) ...
- 465
0
votes
0
answers
44
views
Large objects in the universe sized by gravitational and electrical constants
In a famous talk (from 14:30 to 15:00) Nima Arkani-Hamed tells us that what "fixes the size of the earth" is the equilibrium between the gravitational pressure against the atomic pressure of the atoms ...
- 406
5
votes
1
answer
97
views
Is the Earth orbiting an 'illusory' Sun, owing to the 'speed' of gravity? [duplicate]
We see the Sun about eight minutes after light left it. Presumably this means we are also experiencing the Sun's gravity 8 minutes after it 'left' the Sun.
So are we orbiting around the Sun we can ...
- 3,006
-1
votes
2
answers
69
views
Sun-path on the sky [duplicate]
We are standing on the Earth and we see Sun on the sky. We see it walking in a certain direction, with predictable moving. Earth is a spheroid, as we all know. It is circling around the Sun, and also ...
- 119
0
votes
1
answer
129
views
How does gravity change nearing the core in free fall? [duplicate]
The Pole to Pole Mole Hole-
If there were to somehow be a cylinder going from the North to South Poles, all the way through Earth, then what would happen halfway down (The Core). If something fell ...
-5
votes
2
answers
4k
views
How does Earth hold its atmosphere?
According to Einstein's theory of relativity, gravity is not pulling us down but space is pushing us down. This mean there is no gravity and its an illusion. So, in this scenario how does Earth hold ...
- 109
7
votes
2
answers
1k
views
Does Earth experience any significant, measurable time dilation at perihelion?
Is there any measurable time dilation when Earth reaches perihelion? Can we measure such a phenomena relative to the motion of the outer planets?
- 79
2
votes
2
answers
353
views
Does Earth create gravitational waves on space/time as it turns around itself?
As you know earth turns around itself. At this point can we say earth can create waves on space/time?
- 181
0
votes
2
answers
64
views
What will the effects be of a major water reservoir collape?
Some time ago I heard a comment on some National Geographic or Discovery Channel program that the earth rotation is slowed down due to water trapped in dams I did not pay attention to this at the time ...
- 392
2
votes
3
answers
543
views
How can we explain the position of Mann's planet when travelling on Miller's planet in Interstellar movie?
In the middle of the movie Interstellar, a crew of astronauts land on Miller's planet. For them only one day passed. For the one astronaut left on the station, 23 years passed.
Imagine both look at ...
- 103
1
vote
0
answers
79
views
On the formation of Earth's moon
NASA states that :
The moon was formed ~4.5 billion years ago, about 30–50 million years
after the origin of the Solar System, out of debris thrown into orbit
by a massive collision between a ...
- 111
1
vote
2
answers
4k
views
How attitude indicator (gyro horizon) adjusts to the Earth's curvature?
Image a plane is flying from North to South and is crossing equator. How gyro horizon would maintain correct pitch angle? (Or East-West?)
I assume that pitch angle is correct at takeoff, so the ...
- 13
0
votes
2
answers
2k
views
A function for calculating velocity at several distances as you fall towards the earth's center
Assuming there is no drag, no friction and no other objects affecting you. If you drop into the earth (through a tube). Your velocity will be 7900 m/s at the center of the earth according to http://...
1
vote
1
answer
76
views
What type of instrument can I use to determine my current distance from the center point of Earth?
Immediately, I think of a scale, but is there better way? I can only imagine weighing an object of known mass with an extremely precise scale.
I am asking because I would like to be able to address ...
- 113
2
votes
1
answer
697
views
Are the Schwarzschild metric and the Geodesic Equation relevant in the context of the Earth? [closed]
The geodesic equation used in general relativity is the following:
$$
{\mathrm d^2 x^\mu \over \mathrm ds^2} =- \Gamma^\mu {}_{\alpha \beta}{\mathrm d x^\alpha \over\mathrm ds}{\mathrm d x^\beta \...
- 1,093
-9
votes
3
answers
1k
views
Why doesn't the earth collide with the sun in 64 years?
According to another answer on this site, the time it takes for two bodies in space to collide can be computed with the following formula:
$$\frac{\pi}{2\sqrt{2}}\frac{r_0^{3/2}}{\sqrt{G(M+m)}}$$
...
- 4,494
2
votes
0
answers
135
views
Why In Thermosphere is He and O divided as measured? [closed]
If we look Thermosphere a bit closer. we found out that Helium and Oxygen is divided peculiarily. This picture below shows the Earth looked below the south pole. So the orbiting direction is shown in ...
- 2,449
3
votes
3
answers
217
views
Earth's gravitational waves? Measurable?
Why don't they measure Earth's gravitational waves which has stronger effect holding us on planet and sounds to me maybe stronger instead of measuring far black hole mass created wave 1/1000th of ...
0
votes
2
answers
692
views
Does gravity have two directions?
Imagine a particle that interacts strongly with gravity, but not with any of the other forces, and does not interact with normal matter (this may be analogous to the description of dark matter, I'm ...
- 1,059
16
votes
8
answers
11k
views
How do stars from far away affect Earth?
I know that we obviously get light (or we wouldn't be able to see them), but are there any other ways that they affect Earth and maybe just our solar system in general?
- 341
0
votes
1
answer
120
views
Is there any way to create a globe with gravitational or similar attractive force - earth simulator?
This may sound like a dumb question.
Is there anyway to create a miniature version of earth or its gravitational force.
A globe or sphere which have force inside it which can attract the things ...
- 109
14
votes
4
answers
2k
views
What is the general relativity explanation for why objects at the center of the Earth are weightless?
The idea that as you move through the earth you get a symmetric cancelling of gravitational acceleration which approaches zero acceleration due to gravity at the center of the earth makes a lot of ...
- 1,039
2
votes
0
answers
49
views
The moon affects the motion of the oceans, but can the motion of the oceans affect the moon? [duplicate]
Obviously the earth's oceans have mass and therefore they have an attractive force upon the moon.
However, let's say that we were to cover most of earth with tidal power generators that extract some ...
- 121
0
votes
1
answer
268
views
Gravity Relative to Mass?
Why is it that, in basic physics, it is taught that the acceleration of gravity is the same for objects of any mass (at a constant distance from earth)? Why then is the acceleration of gravity ...
- 113
1
vote
1
answer
122
views
Earth density distribution from shooting neutrinos?
I am interested in possibility of inferring Earth interior structure from gravitational data. As classical calculus problem shows, it is impossible to understand non-uniform density distribution ...
- 13