the force on parts of a extended body in a non-uniform gravitational field due to residual of the 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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1answer
627 views
How can the Moon have such a strong effect on the ocean?
The gravitational acceleration on Earth is approximately $ 10 \mathrm{m}/\mathrm{s}^2 $. Compared to this, the tidal effect of the Moon's gravity gives a local variation in the acceleration of ...
15
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4answers
2k views
Are tidal power plants slowing down Earth's rotation?
Are tidal power plants slowing down Earth's rotation to the speed of the orbiting moon? (1 rotation per 28 cca days)
Are they vice versa increasing the speed of moon orbiting by generating some ...
14
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5answers
1k views
Why does the moon face earth with the same side?
I know this is an astronomy question, but no such stackexchange site exists. So here I am, asking about the physics of the solar system.
I know that the rotation period of the moon equals its ...
13
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2answers
856 views
Why Aren't Saturn's Rings Clumping into Moons?
While reading with my son about how a Mars-like planet collided with the early Earth that resulted in our current moon, it said the initial debris also formed a ring, but that ring ended up getting ...
13
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2answers
241 views
Is the length of the day increasing?
In Frontiers of Astronomy, Fred Hoyle advanced an idea from E.E.R.Holmberg that although the Earth's day was originally much shorter than it is now, and has lengthened owing to tidal friction, that ...
13
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5answers
2k views
Why do we always see the same side of the Moon?
I am puzzled why we always see the same side of the Moon even though it is rotating around its own axis apart from revolving around the earth. Shouldn't this only be possible if the Moon is not ...
11
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2answers
208 views
How large can planets or moons appear?
In many artistic impressions or movies there are pictures or scenes where the sky is filled with an enormous moon (as seen from a planet) or vice versa.
I wonder if there is an upper limit to the ...
10
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5answers
558 views
Why cant one see tidal effects in a glass of water?
Why cant one see the tidal effect in a glass of water like in an ocean?
9
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2answers
623 views
Tidal Lock Radius in Habitable Zones
Much is made of finding exoplanets in habitable zones, locations with orbital semi-major axes permitting water in the liquid state. Habitability may be compromised if such bodies become tidally ...
9
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3answers
1k views
Why does the moon drift away from earth?
I once saw on TV that the moon is slowly drifting away from the earth, something like an inch a year. In relation to that the day on earth what also increase in time.
I wonder why is that?
6
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10answers
960 views
Is the distance between the sun and the earth increasing?
M = mass of the sun
m = mass of the earth
r = distance between the earth and the sun
The sun is converting mass into energy by nuclear fusion.
$F = \frac{GMm}{r^2} = \frac{mv^2}{r} \rightarrow r ...
6
votes
4answers
498 views
Where's earths death bulge, destroying everything in it's path?
I was watching a BBC documentary on space last night. It was talking about gravity, and it said that the reason we only ever see one side of the moon, is because the earths gravity is strong enough ...
6
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3answers
231 views
Tidal force on far side
I have a question about tidal forces on the far side of a body experiencing gravitational attraction from another body.
Let's assume we have two spherical bodies $A$ and $B$ whose centers are $D$ ...
6
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1answer
260 views
How to simulate a crashing wave?
I'd like to create a very rough animation of a wave crashing on a beach. I'm guessing it would have to be a particle simulator, where you code in the forces between the particles and then integrate ...
5
votes
1answer
102 views
Tidal force when planets and smaller objects collide
There are lots of animations on the Web of planet collisions. In most, the planets maintain their (almost perfectly) spherical shape and their surface features right up to the point of impact. In ...
5
votes
1answer
226 views
Determining Average Tidal Effects
Maximum tidal heights vary widely across the globe, from 16 m in the Bay of Fundy to mere centimeters elsewhere. These variations are due to coastline and shoreline differences. This makes it ...
4
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2answers
118 views
If the moon was rapid enough would it be able to orbit the earth from a close distance?
If the moon was close in orbit that it's surface was like 100 km away from the earth's surface. And it had a large enough angular velocity will it be able to hold orbit?
If this was possible, is ...
4
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4answers
331 views
Which gets you first when you are falling into a black hole, the black hole singularity or the cosmic background radiation?
If you look up while you are falling into a black hole you see the universe blue shifted, that is, you see the universe moving quickly forward in time compared to your local time. Since this effect ...
3
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4answers
361 views
Angular momentum power plant on Earth
If tidal power plants are slowing down Earth's rotation then is it theoretically possible to build a power plant that would drain energy from Earth's angular momentum (thus slowing down it's ...
3
votes
2answers
149 views
Where does energy for high and low tides come from?
High and low tides are caused by Moon gravity attracting water. Now there's friction, waves cause erosion, their energy is used in power plants yet the tides work for millions of years and are ...
3
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1answer
47 views
How do the “tidal forces warming moons” theories hold when apart from heating from expansion, there may be also cooling from contraction?
I can understand a temporary heating, from the tital forces exerted on the moon but wouldn't there be cooling as well eventually when particles "give in" to contraction? Wouldn't they eventually net a ...
3
votes
1answer
121 views
Stability of moons around tidally locked exoplanets
Can someone send me pointers to work (either theoretical or simulations)
showing (in)stability of satellite orbits around tidally locked exoplanets?
I want to know firstly if satellite orbits can ...
3
votes
1answer
52 views
Question about tide
Let's say a canal is built in the middle of Kansas in the shape of a ring that stretches 100 miles in diameter. The band of water is 100 feet wide and 10 feet deep throughout the entire canal, and the ...
3
votes
0answers
79 views
Is Earth/Luna tidal lock approaching faster?
Wikipedia pegs the mass of Earth at $5.972\cdot 10^{24}\,\text{kg}$ or $5.972\cdot 10^{21}\,\text{metric tons}$.
Assuming Earth accumulates approximately $30,000\,\text{metric tons}$ annually. To ...
3
votes
3answers
146 views
Tidal acceleration for a retrograde rotation?
Consider two nonelastic spherical bodies with uniformly distributed density, a small such body in a circular orbit around the bigger one.
And consider the smaller body's rotation is matched (as if ...
2
votes
1answer
75 views
How should I be thinking about tides?
I am working on a project for physics that involves tides. This is my current mind set when thinking about tides:
The earth applies a gravitational force on some mass ...
2
votes
1answer
100 views
Can you tell just from its gravity whether the Moon is above or below you?
If you are on a place of Earth where the Moon is currently directly above or directly below you, you experience a slightly reduced gravitational acceleration because of Moon's gravity. This is what ...
2
votes
1answer
161 views
Would the Moon drift away from the Earth due to extraction of tidal energy? [duplicate]
Possible Duplicate:
Why does the moon drift away from earth?
It seems to me that, due to conservation of energy, the moon would drift away from the Earth if humans began extracting large ...
2
votes
2answers
798 views
How gravitation effect on tides
I know that tide is caused by the gravitational pull of moon but what I don't know is how it effects on water. I have actually these doubts.
Why does gravity of the moon creates tides only in water?
...
1
vote
1answer
306 views
Curvature of spacetime in only required to explain tidal forces?
I'm a bit confused about the equivalence principle in GR.
I'm quoting from Wikipedia:
An observer in an accelerated reference frame must introduce what
physicists call fictitious forces to ...
1
vote
2answers
140 views
How important are electromagnetic tidal effects in QFT? Can they be used to determine whether a particle is point-like?
I just did a back-of-the-envelope calculation, which surprised me. I calculated the difference in acceleration (due to repelling like-charges) experienced by two sides of an electron the size of the ...
1
vote
1answer
47 views
Relationship between angular momentum of Earth and recession rate of the Moon
So the problem goes like this:
Two masses $m_1$ and $m_2$ orbit each other with semimajor axis $a$. The orbit is circular, and $m_1 \gg m_2$. The body $m_1$ has a rotational moment of intertia $I_1$ ...
0
votes
3answers
85 views
Stresses in asteroid during close flyby
The acceleration of an asteroid (such as 2012DA14) as it approaches earth is proportional to the reciprocal of distance $r$ from earth center, squared. the derivative of the acceleration, or jerk, is ...
0
votes
1answer
84 views
Has anyone on Earth ever seen the dark side of the moon and if so where are the pictures? [duplicate]
If the Moon rotates then we should see the dark side right? But as far as I know the Moon only shows one side to Earth, how can this be if it is rotating?
0
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2answers
56 views
Saturn ring stabilization
The rings of Saturn are the most extensive planetary ring system of any planet in the Solar System.
I'm wondering, what power is primarily responsible for that stability?
© Public Image by NASA ...
0
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0answers
71 views
Where to go to minimize tidal forces?
Suppose you design an experiment where you need to minimize the effects of tidal forces. Where would you go? There are a few possibilities, and the choice depends on how much effort you are willing to ...
