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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Do all tidal effects vanish in the limit where GR reduces to SR?

I'm an amateur studying General Relativity (GR). A basic question on which I'm still unclear is the sense in which GR reduces to Special Relativity (SR) in the limit. I understand that the laws of SR ...
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Geocentric reference frame and tides

In reading about different frames of reference, and why they are only approximately Galilean frames of reference. The argument for why the geocentric reference frame is not a Galilean was that it ...
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Angular momentum of the earth

We know the tidal waves are decreasing the spin rate of the earth which causes the days to longer, so as the angular momentum of the earth decreases it means it rotational kinetic energy also ...
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What (and if) is the difference in the form of the tidal bulges on the Earth with a smooth surface and the rough surface as it actually is?

It's clear that on a smooth surface of a massive sphere $M$, covered with water, two bulges of water appear when it's rotating in sync with a satellite (a massive sphere with a substantially smaller ...
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What's the antonym for Tidally Locked?

Is there a specific term to refer to celestial bodies that are NOT tidally locked?
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How do tidal forces change gravitational waves

If there is a binary of two neutron stars, they are going to be deformed because of the tidal forces. I suppose that it will cause a change in the movement of the stars and that will cause a change in ...
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Why do I have an extra factor of 3 for self-gravity?

So, I'm trying to calculate the "acceleration" (force / mass) on a spherical object of mass $M$ and radius $R$ due to its own gravity that holds it together. So, here is what I figured. The "...
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Harvesting energy from Moon's orbit without water [closed]

We use the gravitational interaction between the Sun, Moon, and Earth to harvest energy from the motion of the oceans, the tidal "bulge", along coastlines. This uses the changing sea level to ...
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Is a planet hot inside because it is still hot from beginning, or continuously heated? [duplicate]

If a planet emerges from multiple colliding pieces, that causes its material heat up. Later, an existing planet is continuously heated by radioactive decay, tidal forces and other effects. But are ...
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Is it physically possible the existence of moons or planets where objects float permanently above the surface?

I found the following exercise while studying gravitation: A small moon of mass $m$ and radius orbits a planet of mass M, keeping the same face towards the planet. Show that, if the moon approaches ...
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Variance of earth's rotational speed due to tidal effects

I recently watched a video that explained how the length of the day was impacted by where the Earth was at in its orbit around the Sun. Consider a "day" for a point on Earth the period from when the ...
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How the moon takes energy from Earth (if at all)?

At least twice (on the comments of this answer, and mentioned in passing on this book), I have read that the moon takes energy from Earth due to tidal drag. The notion seems that: a) energy must ...
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Making tidal forces “disappear” via coordinate transformations

I'm watching this introductory lecture on general relativity by Leonard Susskind (see 31:50 onwards for the relevant part) [Video title: General Relativity Lecture 1, channel: Stanford]. To give ...
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Tidal forces between Moon and Earth

I started studying about gravitation recently and I came across the fact that when finding the gravitational force between the earth and some point mass in space, we can consider the mass of the earth ...
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What exactly is the energy source of tides?

Tides happen due to the gravitational interactions between the Earth and the Moon. We can say that the tides are pulled by the Moon's gravitational field and so it keeps on changing as it moves out of ...
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What are Love numbers and what is the Moon-Earth tidal quality factor?

I need to find the quality factor (ie. $Q = \frac{\text{energy stored}}{\text{energy dissipated per cycle}}$) associated to the Moon orbiting around the Earth. Looking around for this, lead me to the ...
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Standard explanation of tidal forces

A standard explanation of tidal forces on the earth shows the earth with three force vectors pointing toward the moon. The vector on the side of the earth nearest the moon, Fn, is the largest and the ...
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Is gravitational energy usable and could it be depleted?

Let's take for example a tidal stream generator. We know that tides are a consequence of the Moon gravity, we know that mass is connected with gravity, so is this mean that (1) we use Gravitational ...
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Could a planet experiencing tidal locking have a habitable area?

I wonder if it would be possible that, on a planet that always shows the same face towards the sun, there is a habitable area for some life-form similar to that of the Earth. I guess, since one face ...
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Moon causing tides violates conservation of energy?

It is a simple fact that the moon causes tides in the earth. But these tides seem to be a violation of the conservation of energy. Why exactly would this be? Well think of it the way I am thinking ...
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Is the Moon's rotation affected by Earth's?

There is a lot written on the moon affecting the Earth's rotation but not so much the other way around. I know that moon has its own rotation: Tidal locking is the phenomenon by which a body has ...
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Are black holes affected by tidal forces?

I've recently read about the last parsec problem, which states that supermassive black holes should not be able to merge within the current age of the universe. Once they reach a distance of about one ...
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Buoyant force of tides and conservation of energy [duplicate]

Imagine an electric power generator in a form of a floating object moving up and down and utilizing the buoyant force of sea tides. Can anyone explain how it doesn't violate the principle of ...
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Is mass slowly destroyed when force of gravity is applied? [duplicate]

This may seem like a far fetched idea, but consider this system. Imagine a simple system of just the Moon orbiting around the Earth, creating low tides and high tides with its gravity. Now imagine ...
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How much do ocean currents alone slow Earth's rotation?

Tidal friction is commonly spoken of as the reason for the slowing of Earth's rotation. What if the moon didn't exist? We would still have ocean currents and wind due to the Coriolis effect and the ...
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Can we feel gravity while free falling?

I watched some video saying that there is still gravity in space station and almost same strong as it on Earth, the reason they feel no gravity is because the centrifugal force of the orbit is same as ...
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Are the tides scale independent?

What I mean is the following. Imagine two smooth massive spherical bodies ($M_1\neq{M_2}$), with equal and homogeneous mass densities. Both masses have a layer of water on them for which holds ($R_1$ ...
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Could the moon move balls on perfectly flat and level surface?

I've been looking into the concepts of highly flat surfaces and highly round objects, and I'm wondering if an experiment like this would work / has been done: Take a perfectly flat surface Level it ...
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Will extracting power from ocean tides affect the moon's orbit in the LONG run?

Conservation of energy says that any energy extracted from our ocean's tides would have to come from somewhere. Since these tides are a gravitational effect due to the moon, it would seem that the ...
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Could harm due to spaghettification be mitigated by entering a black hole at almost the speed of light?

Say that we wanted to send a probe into a black hole, perhaps hoping to see if it's actually a wormhole that might transport the probe elsewhere. Upon approaching a black hole, the probe would ...
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Definition of “tidal forces”

May anyone give me definition of tidal forces? Topic is related to force between two celestial bodies which are tidally locked. I have never heard for such force. Here is quotation which is intriguing ...
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Will we be able to experience huge waves one after the other if we were near a strong gravitational field?

I was wondering if we will have huge waves due to the presence of a strong gravitational field nearby earth? If our planet is rotating around the gravitational field, is there a possibility for ...
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Why aren't satellites disintegrated even though they orbit earth within earth's Roche Limits?

I was wondering about the Roche limit and its effects on satellites. Why aren't artificial satellites ripped apart by gravitational tidal forces of the earth? I think it's due to the satellites being ...
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Given that the Moon affects tides and most of the human body is water, do tides affect people?

It is known that the Moon causes tides. Given that the human body is 60%-70% water, is there any research that shows that the tides affect humans in any tangible way? If this is not the appropriate ...
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Pushing a long stick into the event horizon [duplicate]

Imagine a very long continuous stick with one end being pushed into the event horizon, all outside observers must agree that this end of the ruler come to a complete halt while I'm still pushing at ...
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Will tidal effect make physics laws different?

I was reading Wheeler & Taylor's Spacetime Physics. The authors mentioned about tidal effect, as well as all physics laws are same in free-float frame. I am left wondering if tidal effect will ...
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Tidal force of a black hole without using tetrad

One thing I have been somewhat curious about is computing geodesic deviation for tidal effect. Specifically, given separation vector $\xi^a$ between two nearby timelike geodesics and $V^c$ the ...
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When will a person falling into a black hole be crashed by tidal forces?

Assume that a person can resist $30g\approx 300\frac m{s^2}$ (remark: the record is actually at 46.2). I want to solve for the distance $r$ at which a $1.5m$ tall slim person falling radially into a ...
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Does the Jerk (derivative of acceleration) play a significant role in relativity?

In particular, I'm thinking of spaghettification that occurs as an object falls into a black hole (as an extreme example). But what about tidal forces like the tidal heating taking place on Jovian ...
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Can a spacecraft use the planet's gravitational gradient to boost it's orbit without rockets?

A spacecraft orbits a planet. It extends a mass about a horizontal direction on a long tether. At this point there is not much gravitational gradient between the craft and the ejected mass so there is ...
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Why does a tidal bulge result in a net torque on the Moon?

I understand that a tidal bulge is caused because the side of the earth facing the moon experiences a stronger gravitational force than the other. This results in the oceans on that side slightly ...
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If you fell into a black whole with an accretion disc, but perpendicular

If you fell into a black whole with an accretion disc, but orthogonal to the plane of the disc - would you ever meet the disc? I'm not asking whether you survive long enough, and obviously we assume ...
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Is gravitation on earth less in nighttime than in daytime?

I have been thinking on the effect of the centrifugal/centripetal forces from the orbital movement of the earth around the sun, which might perhaps affect the gravity. In nighttime we are on the ...
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Tidal acceleration of a body at rest in a Schwarzchild geometry using geodesic equations

I'm self-studying the properties of a Schwarzchild geometry, with line element $$ds^2 = \left(1-\frac{2m}{r}\right)dt^2-\left(1-\frac{2m}{r}\right)^{-1}dr^2-r^2\left(d\theta^2 + \sin^2\theta d\phi^2\...
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If the Earth would change into a ball of water, how wil its form develop, considering only the Sun's and Moon's influence? [duplicate]

Let's fantasize that the Earth changes in a non-rotating ball of water. And let's assume the only gravitational influences on it are those of the Sun and Moon. What will happen to the form of the ...
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What happens to the water on the surface of the Earth if the Earth is not rotating about its axis in the Earth-Moon system?

Suppose the Earth is not rotating. As usual, the Moon follows its normal path around the Earth. Let's assume it's a circular motion and that there are no other gravitational influences. A test ...
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What would happen to a person's body if they entered a black hole? [duplicate]

One of the premises of the classic sci-fi show Farscape is that a person could travel through black holes, I'm curious as to what exactly would happen to a person body if you were to enter a black ...
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Where does the energy from tidal power plants come from? [duplicate]

Tidal power plants taps into the energy in the motion of the oceans due to the gravitational interaction between the earth and the moon, so much is clear to me. This question is about where would this ...
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Why is angular momentum of the Earth/Moon system conserved?

Why is the angular momentum of the Earth/Moon system conserved, apparently unaffected by external forces such as force of the Sun?
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How can the tidal force due to a black hole tear apart the observer inside?

I have heard that the tidal force of a black hole can tear apart an observer. But if the spacetime fabric is really stretched out near a black hole, isn't the observer also a part of it? Surely, he is ...

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