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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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Formula for horizontal compression caused by tidal acceleration [closed]

I understand how tidal acceleration separates objects falling vertically into a gravitational field. This has been covered many times and derived nicely here. $$\Delta F = 2G \frac{Mm}{r^3} \Delta r.$...
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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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Is the shell theory, at least in concept, applicable to a ring world?

The Shell Theory tells us that inside a homogeneous sphere there is no gravity. It seems to me that if you cut off the top and bottom of the sphere and leave a ring, equal in width from the equator ...
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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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1answer
38 views

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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Does water height in mixed semidiurnal tide systems change in a sinusoidal pattern between peaks?

I'm writing a bit of plotting software that takes the time of high tides and low tides and interpolated what the height should be between these times. I know that diurnal tidal systems follow a ...
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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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Relative size of the 2 tidal bulges

I am interested in making a simplified model that represents only the effect that the moon has on Earths tides. In this model I am going to assume that the earth is completely spherical (with no ...
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3answers
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Is the path that a planet takes orbiting the sun a centripetal one or one that follows a geodesic path?

Is the path that a planet takes orbiting the sun a centripetal one or one that follows a geodesic path? My point is that if the planet follows a centripetal path all objects on the planet will ...
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How long and to what extent can tidal energy sustain a productive system?

I've been idly re-reading some articles lately on Enceladus and Europa. Regardless of the prospects for the actual existence of life in their oceans, it spurred some thinking on how systems reliant on ...
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Difference between solar annual and solar daily earth tides

I understand there is a semi-daily and daily solar earth tides (S1,S2) because the earth is rotating around its axis. I understand there is an annual and semi-annual solar earth tides (Sa, Ssa) ...
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Deriving the expression for the static equilibrium height of liquids under tidal force

I have tried looking at various sources and Wikipedia articles. I also checked some Q&As here at StackExchange but I couldn't quite grasp how the formula for the height of tides is derived when we ...
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Understanding the tidal force tensor

I'm just looking to gain a basic intuitive understanding of the forces at work in tidal stripping and their direction/motivation etc. I'm struggling to grasp the underlying principles and it is making ...
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1answer
83 views

Where does the work come from if tidal forces are stretching elastic objects?

An elastic object e.g. a rubber band will be stretched in accelerated expanding FRW-spacetime during radial free fall in Schwarzschild spacetime by tidal forces due to Ricci- and Weyl-curvature resp.,...
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2answers
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If gravity is not a force, how come it can produce potential energy?

From my poor understanding of Einstein's theory of relativity, gravity is not a force but the consequence of mass curving the space-time continuum. As such, the moon revolving around the earth is ...
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Energy from tidal waves [duplicate]

We all know that the Moon orbits around the Earth, and that this happens because the kinetic energy from the Moon is enough to "deny" Earth's gravity but not enough to escape its orbit. If I'm not ...
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Calculate Height of Ocean Tides if Earth Had a Larger/Smaller Radius

For context, I'm coming at this question from the Worldbuilding stackexchange, where I've posted a related question. I'm not a physicist or scientist by training, so if I make any glaring errors, ...
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1answer
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Debris ring formed from breakup of extreme-high rotation rate of rigid ring

In Larry Niven's Ringworld, where there is a rigid rotating ring with a radius of 1AU with the Sun at the centre, he introduces a fictional material "scrith", which apparently is strong enough to ...
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2answers
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Would it be possible for a human to simply “step” through a traversable wormhole?

(For the purposes of a science-fiction story where the author is attempting to have as much basis in fact as possible) if one were to create or make use of a Morris-Thorne or similar traversable ...
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Are the high tides always more unequal when the centre of gravity is within a planet?

In case of our high tides at both sides of the Earth it seems that they are almost equal. But is there a slight difference because the center of gravity is about 1,700 km below the surface of the ...
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During Tides what is the jerk or rate of change of acceleration on the surface of the water?

Wikipedia defines tides as the change of sea levels due the inertial and gravitational effects of the moon. But have there been any measurements during the tides of the jerk on the water? Could one ...
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What happens inside the black hole?

I have learned that whenever an object gets inside a black hole, it traps the object and sucks it inside. After it had been swollen by a black hole, what would happen to the object inside it?
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1answer
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Does the moon rotate around the earth-moon axis?

It is well known that the moon always shows the same side to the earth. But does the orientation of this side change? I.e. does the moon rotate around the moon-earth axis?
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Estimating the curvature tensor of spacetime using a rotating body

In curved space, you can define the Riemann curvature tensor at a point. In Riemann normal coordinates with that point as origin, the Riemann curvature tensor can be expressed as depending only on the ...
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2answers
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Increasing distance between Earth and Moon [closed]

I have a problem where a planet's rate of rotation is decreasing due to tidal effects of the moon. I know that the angular momentum of the system will be conserved. So, in order to conserve that the ...
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1answer
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How far apart are two initially $1000m$ separated bodies that fall to earth from infinity, when the closest body reaches earth?

Imagine two bodies (very, very small compared to the size of the earth), 1(km) separated from each other (in the direction of the earth) at infinity. After they reach earth after an infinite long trip ...
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3answers
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Can the gravitational force between a 2D ellipse and a point mass in 3D space be found using the centre of mass of the ellipse?

I have a question where I need to find the gravitational force between an ellipse of negligible thickness and a point mass with given coordinates in 3D space. Not being from a physics background I ...
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1answer
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Rapid deceleration of the spaceship with the help of black hole [closed]

Could a spaceship traveling close to the speed of light (ok, maybe speed is not relevant for this question) decelerate (almost stop) very quickly (say, on a safe distance) with the help of a very ...
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Laplace's tidal equations

Do you know where to find a clear, pedagogical derivation of Laplace's tidal equations for the tidal elevation $\zeta$ and the velocities $u$ and $v$ of a fluid sheet located on a rigid body?
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Spaghettification inside a black hole?

Taylor and Wheeler in "Exploring Black Holes" calculate that the spaghettification time, measured from feeling a 1g tidal difference head-to-toe to disintegration at the singularity, is a constant, a ...
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How large would the tidal effect on a tube of water be?

I was wondering how large the tidal forces on the water inside of a tube would be. The image from this answer explains what I am thinking of visually: https://physics.stackexchange.com/a/46246/170918 ...
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Tidal force - what's actually correct? Vector forces or the gravitational differential explanation

I'm trying to understand tides. But it seems like my sources and myself is a bit confused. In the Space-Times explanation on YouTube, he claims the ordinary explanation of gravitational difference ...
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3answers
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In the middle of two great masses [duplicate]

Imagine that I'm exactly in the middle of two identical masses. So that each of them exerts an identical acceleration on me and in the exact opposite direction. My question is Will these opposite ...
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Is the law of the equality of inertial and gravitational mass valid in all possible cases? [duplicate]

I have been thinking about equivalence principle (EP) for a while and I am intrigued about the following. A classical example to explain EP: On the one hand, imagine we have an elevator (e_1) ...
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2answers
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Do tidal forces affect the poles?

In many tidal forces illustrations it seems like the poles (with respect to the satellite's rotation) are drawn towards the center of the body. I can't understand why that is. Is it because the body ...
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1answer
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Constant of integration in Equilibrium Theory of Tides

I am preparing an elementary derivation of Newton/Laplace's equilibrium theory of tides. The derivation of the tractive force is understood, as is the derivation of the differential equation for ...
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1answer
309 views

Expanding Moon's orbit and newtonian mechanics

the 2 body problem of earth and moon is suppose to be perfectly described by Newtonian mechanics / Kepler's laws. How ever the moon's orbit is been moving away from earth in contradiction to the ...
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1answer
226 views

Orbital pendulum (librating moon dumbell model)

Consider a moon orbiting its planet on a circular orbit. The moon is tidal locked to its planet, and has two permanent bulges, not exactly aligned with the planet. According to Newton's theory of ...
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1answer
143 views

Why is the Earth still spinning? [duplicate]

I understand that scientists believe the earth and the moon were spinning at the same speed as each other at the time they experienced acceleration (were formed). I also know that the reason given for ...
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1answer
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If Earth spun the other way, would the Moon be pulled closer by tides?

I read this answer and thought “that’s not right”. But thinking that the moon would continue to receed and the Earth torqued in the same direction (speeding up) doesn’t balance kinetic energy. I ...
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Is this derivation for the development of two opposite two bulges of water due to the circling of two bodies around their CM right?

I tried it this way. Consider two equal spherical masses M, covered with a layer of water, circling around each other at a distance $l$ (measured between their centers). They have radius $R$ and ...
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2answers
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Does an object falling from very large height as compared to radius of Earth rotate as well due to gravity?

If let us say a rigid body is falling from a height such that value of $g$ remains same then the body does not rotate at all about the centre of mass as centre of mass and gravity coincide hence net ...
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Will an object orbiting a non-rotating mass with a layer of water on it cause two bulges of water on opposite sides of it? [duplicate]

Imagine a non-rotating spherical mass with a sea on its surface (somewhat like the earth, except for the rotating part). Around this mass is circling an object with a much smaller mass, but ...