# 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 would black hole rip me apart?

According to my understanding of General Relativity, gravity is not a force and an observer which is falling freely under the influence of gravity should be considered inertial. Now, I have come ...
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### Can a human pass through the event horizon of a supermassive Kerr black hole without being shredded? [closed]

Let's say a supermassive Kerr black hole with a mass of $1.78\times 10^8 M_{\odot}$ and a spin of $a \approx 0.99999999999999 M$. What would the tidal forces be on a human crossing the event horizon? ...
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### Is the gravitational tidal force equivalent to expanding space?

If you fall towards a black hole, the particles in front and the back of you, in the direction of the center, are accelerating away from you. So, seen from a freely frame, can we say that space is ...
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### Problem calculating tidal deformability in GR

everyone. I am trying to calculate tidal deformation of a neutron star (NS), only keeping linear terms like it was done in Hinderer's papers https://doi.org/10.1086/533487 and https://doi.org/10.1103/...
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### NASA's explanation on tidal acceleration

I've found an animation in NASA's website, illustrating tidal acceleration effect between the moon and earth. It's the forth animation from the top in this page: https://moon.nasa.gov/moon-in-motion/...
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### How does Schwarzschild spacetime bend a free falling rigid body?

How does Schwarzschild space-time bend a free falling rigid body? Will it be stretched or squeezed? How much it will be modified? Can we find an effect of Lorentz contraction? When will the assumption ...
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### Tidal forces in daily situations: where to find it?

I'm trying to look for something that I'm not used to. My search is related to Tidal forces and the purpose is: making a qualitative explanation (@ High School level) of this phenomenon, using daily ...
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### Tidal force in equivalence principle

The inertial frame of reference in a gravitational field is defined locally, but couldn't a sufficiently sensitive instrument detect tidal forces in the gravitational field and thus make the frame in ...
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### Are there tidal forces between the solar system and the galactic centre?

Tidal forces are experienced within a system moving in free fall around a bigger object because of the different strength of gravity over the system. The difference can be calculated between the far ...
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### Could a moon keep orbiting a planet forever?

Our Moon orbits the Earth further away each year due to the tidal forces but could there be a moon orbiting a planet where somehow keeps going further away by the tidal forces but its attracted again ...
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### Smallest pool to form tidal wave

Tidal waves form in the ocean, while not in my swimming pool. I wonder what's the smallest swimming pool is like to form tidal waves. It's true that tidal wave always exists, let's assume we want a ...
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### Gravity contradicting conservation of energy? [duplicate]

If we could utilize gravitational force to create energy, could gravity, being unlimited, generate unlimited energy? Consider electricity generation from tides. Since tides are due to gravity, aren't ...
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### How long would it take for the moon to disintegrate into a ring if placed inside the Earth's Roche limit?

Wikipedia says the Earth-Moon rigid Roche limit is about 9500 km. The moon's diameter is roughly 3500 km, so say I magically teleport the moon to within 6000 km of the Earth—it's fully contained ...
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### What is the physical meaning of self-attraction and loading (SAL) in tides?

I came across the term self-attraction and loading (SAL) in many papers about tides. However, I don't understand the physical aspect of it. According to what I understand, self-attraction refers to ...
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### Roche limit and satellites orbiting each other

Does the Roche limit apply also to two satellites orbiting each other or only to individual satellites held together by gravity? For example, I have a tungsten little ball (10 cm in diameter) around ...
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### Could a set of rogue double planets (binary planets) be habitable due to tidal forces?

I want to write a story about rogue double planets and was wondering if it's possible to have a double planet where either both or one of the planets are habitable due to tidal forces even if the ...
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### Physical effects due to the mass of the moon suddenly going to 0? [duplicate]

A gedanken experiment - imagine the moon's mass instantaneously went to 0 ; what would happen?
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### How does general relativity explain tides?

How general relativity explains tides using spacetime curvature? and if the full moon can affect water, inside the international space station did the ever observe small things like water droplets ...
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### Derivation of Roche Limit

In calculation of the Roche limit between the two celestial body, tidal force on small mass $u$, $F_t$ is expressed approximately as $$F_t=\frac{2GMur}{d^3}$$ While deriving $F_t$, what's the reason ...
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### Earth, Moon, gravitatioal pull

Does the gravitational pull that causes tides, also affect the Earth's land mass. Does it affect the atoms, molecules, is there a slight bulge to the actual Earth / Land itself?
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### Weight dependency on the location on Earth relative to Sun

In this post a theoretical physicist says that one will weigh less at the point on the Earth closest to the Sun due to the Sun's gravity, which makes sense to me. But he also says that one will weigh ...
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### Will the increasing distance between Moon and Earth result in speeding up or slowing down of Earth's rotation period?

Problem The Moon tidally brakes Earth's rotation, and as a result distances itself away from Earth as a result of conservation of total angular momentum*. Certainly, tidal braking slows the rotation ...
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### Can an observer in a double tidal locked system figure out it is orbiting?

Tidal locking, when the spin rate of a body matches the orbital rate so that it always faces the other body with the same side, usually occurs for just one of the bodies in orbit. However, there are ...
1 vote
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### How does one calculate the tidal force in the throat of a wormhole?

If you were to attempt to open a wormhole from Earth to Alpha Centauri (4.37 LY), and its throat were to be a radius of 1m, while its mouth were to be 1.5m radius, how many newtons of force would be ...
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### Tidal Forces on a Body at a Fixed Altitude

It's a thought experiment which I've been running in my mind for long in order to understand tidal forces. Any suggestions/ideas are appreciated. Assume a perfectly spherical planet with no atmosphere....
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### What is the difference of gravity between lowest tides and highest tides?

I know tides are due to gravitional gradients so the difference of gravity between places does not need to be big in order to generate tides. Regardless, what difference are we talking about, ...
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### What are tidal forces inside a black hole?

It seems to me that a body under the event horizon of the black hole should not experience any tidal forces, because the singularity is not in any spatial direction from the body but in the future. As ...
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### Do tidal forces create atmospheric jet streams?

Earth's large-scale wind patterns (a.k.a. jet streams) are generally attributed to "differential heating" by the sun. But the large-scale patterns in Earth's oceans (a.k.a. tides and tidal ...
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### Struggling to prove Newton's Law of Gravitation starting from smaller bodies

I have seen at least four different posts in this website in which the OP asks for a proof of Newton's Law of Gravitation (often without stating from which axioms the proof should start) all of which ...
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### How does tidal locking work if planets are almost perfect spheres?

I guess this question has more to do with orders of magnitude than actual theory but as I understand, planets like mercury are almost perfect spheres with very minor deviations. For instance, ...
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### Do black holes rip apart even atoms and protons and neutrons?

I am aware that black holes rip apart objects because of spaghettification. What about atoms and protons and neutrons? Do they get ripped apart too? But, in the case of protons and neutrons, wouldn't ...
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### How are relativistic tidal forces different from their Newtonian counterparts?

Conceptually, the tidal effects of Newtonian gravity differ drastically from that of general relativity. In Newtonian gravity, the effect is due to the change in gravitational force across a certain ...
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### How much of the Tidal Energy can be attributed to the Sun?

I'm been researching this question but haven't been able to find a conclusive answer. As I understand it, there are two forms of tidal energy: tidal potential energy and tidal current energy. Tidal ...
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### Spaghettification - Singularity is just energy?

So... as matter falls into a black hole the tidal forces tend toward infinity as you get closer to the singularity. These tidal forces overcome the bonds between atoms, then the bonds between nucleons ...
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### Do you really die if spaghettified by a black hole?

Considering gravity acts by stretching spacetime and all forces (EM, nuclear etc...) are relative to spacetime, can we then consider that regardless of how stretched you are to an observer outside the ...
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### Does a experiment measured in free fall here on earth and inside a black hole gives the same result?

According to Einstein equivalence principle observer in free fall measure the same thing in experiment made in their laboratory frame. Let us take for example the probability $P$ of an hydrogen atom (...
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### If I jump into a black hole, will I see myself passing event horizon? [closed]

Given a black hole with mass of the Milky Way (1.6x10^42 kg), I built a frame that 1 m above the event horizon. I am jumping from this frame my legs down (since I am afraid to dive into a dangerous ...
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