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Questions tagged [tidal-effect]

The force on parts of an extended body in a non-uniform gravitational field, due to residual gravitational attraction between the overall effect on the body and the expected effect on the point in question. Tidal forces are most notably in large moons orbiting near their primaries.

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Why does a moon's orbit get more circular with time?

I understand that there is a transfer of energy between a moon and a planet depending on whether the moon is orbiting faster or slower than the spin rate of the planet. This would obviously change the ...
Jack R. Woods's user avatar
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Would the Moon move away if the Earth were frozen with no liquid tide?

The moon is moving further from the Earth. To the extent that after 600 million years we will no longer enjoy full solar eclipses as it will be too far away to completely block the sun. The reason the ...
Francis Cagney's user avatar
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When do we talk about spaghettification or pancakification in black holes?

So I've been doing some research for a while now, and yesterday came across the video of PBS space time talking about what happens to quantum information in a black hole. In the thought experiment ...
Anais-Ellie Gucek's user avatar
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Despite tides the Moon, as far as I know, doesn't slow down. Where does the energy come from? [duplicate]

Hy, I don't have anything to do with physics, so please forgive me if I explain my question in a weird way ;) As the Moon rotates around the earth it is creating tides and waves on the earth. IE it's ...
Jakob S.'s user avatar
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What's the proper way to calculate neap low tide and high tide tide-raising forces?

My coursemates (and maybe, through them, my professor) insist that to calculate the neap low-tide tide-raising forces, I should take $F=\frac{GMa}{d^3}$ for a point on the earth $90°$ from the nearest ...
sflannery's user avatar
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Tidal forces in the early solar system

I'm reading a book called "Gravity from the ground up" by Bernard Schutz. I don't understand this section from Investigation 13.3 on page 159, which discusses the formation of the solar ...
user3327311's user avatar
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Tidal bore during hurrican Ian [closed]

Hurricane Ian destroyed a railroad bridge several miles upstream of the mouth of the Caloosahatchie river. The pilings for the bridge were snapped off which would seem to indicate a massive ...
John Sundermeyer's user avatar
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1 answer
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Is the tidal force at the Roche Limit equivalent to the gravitational force of the body?

There is a pebble on the surface of the earth facing a massive celestial body. If the tidal force becomes equal to 9.81m/s^2, Then it will float. Would this be at the Roche Limit then? Does that mean ...
TheJeran's user avatar
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Is the tidal force the only real force-like quality of gravity?

The force we feel when standing on the Earth is electromagnetic in nature. We are accelerated upwards without a coordinate acceleration following due to the curvature of spacetime (that would be the ...
Il Guercio's user avatar
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Does the Weyl tensor amount to tidal effects of gravity?

The Ricci tensor, for the spacetime surrounding the Earth, is zero, so the spacetime around the Earth is Ricci-flat. The Riemann tensor though is not zero since spacetime certainly is curved. This ...
Il Guercio's user avatar
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How to calculate tidal bulge on a shallow, enclosed body of water?

The moon causes a tidal bulge because there is a differential in the gravitational field on the near vs far side of the Earth and the ocean is fluid and can distort to seek the new equilibrium state ...
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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 ...
spraff's user avatar
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Interplay between gravity and cosmic expansion causing collapse of large-scale structures?

As far as I understand it, in the context of large structure formation, the interplay between gravity and cosmic expansion can cause certain anisotropies in voids that can make them collapse (https://...
vengaq's user avatar
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How can tides even of miniscule magnitude occur in inland lakes?

Ocean water is flexible enough to allow water from each side of low tide to flow to the sides of high tide. So for a high tide, there must be a low tide somewhere else from where water is drawn out. ...
Curiosity's user avatar
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What happened to Newton 3rd law if our Moon is moving away at 1.5" yearly? [closed]

Our Moon is going away and I read that it is the culprit is our ocean, but then what happens to Newton 3rd law there should be an equal and opposite forces too so where's that? Is it absorbed by the ...
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Black Hole Ripped Apart

Could a black hole be ripped apart if it passed directly between two other black holes that were millions of times bigger?
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If the tidal bulge on the earth speeds the moon up, how does the moon move to a higher orbit?

I understand that the moon causes a tidal bulge on Earth, and this tidal bulge moves slightly ahead of the moon due to Earth's rotation. When reading about why the moon is moving away from the Earth, ...
WillowRook's user avatar
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Does dark energy increase tidal forces in cosmic voids...?

I would like to ask you some questions I have about some interesting work I was reading (https://arxiv.org/abs/1205.4238 & https://academic.oup.com/mnras/article/527/4/11962/7457744) where the ...
vengaq's user avatar
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Why are tidal forces conformally invariant?

Tidal forces are encoded in the Weyl-tensor $C^\mu_{\nu\lambda\sigma}$. It is well-known that the Weyl-tensor is invariant under conformal transformations: $g'_{\mu\nu}(x) = \Omega(x)g_{\mu\nu}(x)$. ...
Frederic Thomas's user avatar
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Non-equilibrium tides and tidal flow fields

For i) an ideal rotation ellipsoid entirely covered with a thin shell of water ii) locked mutual rotation iii) non-rotating earth iv) further conditions (?) the idea of equilibrium tides with a ...
TomS's user avatar
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Would I accelerate in the same direction as my friend inside the event horizon?

Imagine my friend and I fell into the event horizon of the Gargantua, the blackhole from the movie interstellar with the mass of 100 million times of our Sun. Would I be able to tell that both of us ...
user6760's user avatar
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Einstein equivalence principle conflict

The weak principle of equivalence says that freely falling towards the Earth is the same as being in space far away from any stars. However, imagine that you are freely falling on a planet with $g=9\...
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Does earth revolution speed slowing down because of small drag from space is not empty?

I read that universe is not empty, in least dense parts has 1000 atoms per cubic meter, does that slow down earth speed? Why these atoms are there, why they are not attracted by surrounding gravity ...
22flower's user avatar
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Would ocean tides on the moon of a gas giant really be kilometers high?

I was reading an article on exomoon habitability constrained by illumination and tidal heating. The article imagines an Earth-like exomoon around Jupiter-like host planet. That got me thinking about ...
Boreal Stars's user avatar
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Hills Mechanism

The Hills mechanism postulates that when a stellar binary system is perturbed by a supermassive black hole (SMBH), the tidal forces at play result in the capture of one star while simultaneously ...
RKerr's user avatar
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Can gravity of planets besides Sun and Moon affect tides on Earth?

The tides in some places on Earth are over 50 feet. If the gravity from Venus had a ten thousandth the affect of the Sun and Moon on a 50 foot tide it would make a difference of one twentieth of an ...
JohnTrainor's user avatar
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1 answer
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Tidal effects of galaxies orbiting one another in presence of dark energy?

I recently asked this question about whether there was a "distance" between two galaxies where both the gravitational force and the influence of dark energy would be balanced. The answers ...
vengaq's user avatar
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1 vote
1 answer
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Closest possible flyby to a nonrotating supermassive black hole

Imagine you think Laplace is the last word on black holes. That is, you are aware of the radius for which the escape velocity is $c$, but you think gravity is Newtonian. You set your spacecraft on a ...
Mark Foskey's user avatar
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3 votes
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Can fictitious forces always be described by gravity fields in General Relativity?

I was debating a geocentrist online who said that Einstein and a bunch of other physicists admitted a geocentric framework is valid. I replied that this was technically correct, but if you wanted to ...
CyborgOctopus's user avatar
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Will the moon ever proceed to lose its orbit and hit the earth?

Assume that the moon it orbiting the earth in a circular trajectory. It will experience an acceleration directed towards the centre of the earth given by $\frac{GM}{R^2}$ where $G$ is the universal ...
Orpheus's user avatar
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Why does the Earth move away from the Sun?

From the (Wikipedia's) definition of the astronomical unit $AU$, we have that it is defined as: $AU=\sqrt[3]{\dfrac{GMD^2}{k^2}}$ Where $k\approx0.01720209895$ is Gauss' gravitational constant, $G$ is ...
Antoniou's user avatar
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1 answer
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Can we design an experiment or an intuitive way to demonstrate tidal locking?

I was explaining the tidal locking phenomenon to a friend. First I started with the formation of solar system and how at the beginning the planets were actually like balls of magma-esque rocks. And ...
polfosol's user avatar
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3 votes
3 answers
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Negative energy particle effect on observable object

A recent paper "Gravitational Pair Production and Black Hole Evaporation" (discussed in short here) says that any spacetime curvature would produce Hawking radiation, no need for event ...
Vashu's user avatar
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1 answer
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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 ...
1 vote
2 answers
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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 ...
user1583209's user avatar
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4 votes
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Book recommendation for classical Newtonian gravity

I’m looking for a good textbook that covers Newtonian Gravity in detail (preferably advanced undergrad/grad level). One that covers important things like Calculating trajectories of satellites around ...
-1 votes
1 answer
78 views

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 ...
Adventures of an Amateur Astro's user avatar
1 vote
2 answers
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Would bending of spacetime make tides an invisible effect? [closed]

Similar to this question: How does general relativity explain tides? But I’m specifically interested in if General Theory of Relativity would predict that bending spacetime means the water and land on ...
Daniel Harris's user avatar
6 votes
2 answers
2k views

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? ...
Hjan's user avatar
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17 votes
6 answers
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How can a grain of sand be "spaghettified" when nearing a black hole?

I have a hard time wrapping my head around this "spaghettification" process that apparently takes places when getting close to a black hole. Gravity is proportional to the distance of the ...
d-b's user avatar
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5 votes
1 answer
49 views

How big can a sphere of water in low earth orbit get?

Imagine that you have a large space station in low earth orbit, and inside that space station is a large sphere of water. How big can that sphere of water get before tidal forces overwhelm surface ...
blademan9999's user avatar
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1 vote
1 answer
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If two black holes orbit around each other should their tidal forces cause a shrinking of the closer parts of their event horizons?

I recently asked a question about the influence of external gravitational fields on the stability of the geometry of a part or all the event horizon of a black hole. I understood the answer in a ...
Krešimir Bradvica's user avatar
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Is tidal energy an infinite source of energy?

As tidal waves are caused due to gravitational force which acts infinitely until the presence of mass (the Moon) which make me think of an infinite source of energy. So what's wrong in here?
Omkar kharat's user avatar
3 votes
1 answer
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What are the consequences of the tidal friction on the galaxy?

In the Earth-Moon system tidal-friction slows down the rotation, so does it do the same for the galaxy? If not how come, and why it's different than on Earth? If so can this slow-down be the reason ...
zebra's user avatar
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How do tidal forces on incomplete geodesics determine extendability?

Why can we be sure that the manifold with the metric $(M,g)$ does not have a geodesically complete extension if it has an incomplete timelike geodesic along which the tidal force blows up? Does this ...
Ozzy's user avatar
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1 answer
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Why is the time difference of equal tide states not 50 minute if one lunar day is 24 hour and 50 minutes?

I do understand that tidal forces are caused by de difference of gravitational force between both opposite points of the earth where a bulge is formed. I do understand that a lunar day is ruffle 24 ...
Kagawa Kisho's user avatar
1 vote
0 answers
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Can we find out if we are uniformly accelerating through flat spacetime by looking at non-accelerating clocks? [closed]

The equivalence principle states that locally you can't tell if you are accelerating through flat spacetime or are at rest in a uniform gravitational field. Does this mean you can only tell the ...
ErnieB's user avatar
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1 vote
2 answers
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Do extended bodies in a gravity field fall slower or faster than point-like structures?

The weak equivalence principle states that all point-like particles fall along the same in a gravity field. If a body is extended it experiences a tidal force which causes the bodie to elongate. If ...
ErnieB's user avatar
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2 votes
1 answer
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Will two passing bricks in empty space induce rotation in one another?

Two identical rectangular bricks with mass $m$ pass each other anti-parallel in empty space with a constant velocity $v$. Say the smallest distance between them is $s$. Assume the bricks to be aligned ...
Gerald's user avatar
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If the Earth and the Moon were smaller, would moon tides be more or less intense?

If the Earth and Moon were smaller (and everything on them too, but keeping the same average density and the same "relative" distances, I mean... the same proportions!), would the tides ...
jainemarie's user avatar

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