Questions tagged [gravity]

Questions regarding the attractive force which exists between any two bodies of matter.

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Spacetime superfluid [closed]

I was wondering if space-time was a superfluid ,and energy excites the particles which make up this superfluid we cannot do experiments in particle accelerators just the energy is too high there.In ...
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Can air/gas be slowed down by friction [closed]

Can wind/air that is moving at average speeds be slowed down by the cause of Friction? Also, Can Air bubbles in water be slowed down because of Friction? Please cite your sources.
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This article says the moon may start moving closer to the Earth in the distant future; could this be true?

Bruce Dorminey wrote an article for Forbes with the title of "Earth And Moon May Be On Long-Term Collision Course". The article notes: "For now, our anomalously large Moon is spinning ...
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How spaghettification is possible at the Event Horizon of a supermassive black hole?

if gravity is too strong then it will break a object apart as gravity is strong enough to break the chemical composition of object why we consider "Spaghettification" relevant in this case ?
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Would you fall down faster on Mars or on Earth? (and how would that compare to Venus?)

You're flying in a hot air balloon, reaching the altitude of $10\textrm{ km}$, having an adamantium skeleton and superfast regenerative abilities, you jump down without fear of hitting the ground. ...
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If the Sun disappeared, could some planets form a new orbital system?

If the sun were to suddenly disappear, the planets would continue to travel tangentially to their former orbits. (This I know from this answer to a somewhat related question here.) In such a scenario, ...
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Orbital decay via gravitational emission in a hypothetical, two-body universe

Assume we have a universe with nothing in it except for two objects. One of them is a stationary object that is perfectly spherical with the mass of the Moon (without any atmosphere, of course; also, ...
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How do pressure, temperature, and gravity affect a smaller body than Earth with the same bulk composition?

Earth has a density of about ${\rm 5.513 ~g/cm^3}$ with one Earth radius and one $g$. Venus, a very similar planet to Earth and likely with about the same bulk composition, has a density of about ${\...
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How much lighter would someone be on the Jupiter-facing side of Io?

Io is the Galilean moon closest to Jupiter. Its average surface gravity is 0.183g and it has a tidal lock with Jupiter. So if you stood on the near side of Io at the equator, how much lighter would ...
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In 'Modified gravity' theories like MOND, are galaxies and stars actually, slowly accelerating? In the normal sense? normal

In M.O.N.D., they say that massive objects, accelerating slowly, experience this modified gravity... But, are they actually gaining in velocity, albeit very slowly? Or are the MOND theorists using the ...
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Will there be any more planets come into our solar system and make it their “home”?

Could we have more planets come into our system and get trapped by our suns gravitational field and rotate?
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New evidence against the existence of dark matter?

I've just read and heard about an article which gives new evidence for MOND - Modified Newtonian Dynamics, which is an alternative to dark matter by proposing that our gravitational law should be ...
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Recent research regarding if the local group of galaxies will remain bound to the Virgo Cluster?

The question of if the local group of galaxies will remain bound to the Virgo Cluster has been asked before (Is the local group bound to the Virgo cluster?). I am wondering if there is any more recent ...
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I need to study space, planets and black holes, how do I study them on my own [closed]

I need to study space, planets and black holes, how do I study them on my own, knowing that I am an Arab and I do not know English. I use translation applications. I speak with you. Can you help me ...
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Will 1036 Ganymed's orbit be changed by its close encounter with Mars in 2176?

In 2176, the asteroid Ganymed will come as close as 0.02868 AU (4,290,000 km / 2,670,000 mi) from Mars. That's pretty close to Mars imho. Can Mars' gravity alter Ganymed's orbit significantly in 2176 ...
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How to conceptualize the strong equivalence principle (SEP) in the context of stellar motion in an extragalactic galaxy?

In the theory of general relativity, the SEP states all the laws of nature are the same in a uniform static gravitational field and the equivalent accelerated reference frame. I've been reading the ...
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Is Jupiter really shepherding the main belt, and Neptune the Kuiper belt?

By "dominating another object's orbit" my understanding is that the most massive body's gravity has so much influence that, when they come close, it makes the other body/bodies' orbits shift ...
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What is the mass for a celestial body to definitely achieve hydrostatic equilibrium?

While these posts (attempt to) answer what the minimum mass is to be able to achieve an ellipsoidal shape, my question asks for the mass at which a body definitely collapses into an ellipsoid. Meaning,...
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Do some galaxies collide faster than the speed of light?

If some galaxies expand away from each other faster than the speed of light then do they collide faster than the speed of light? Update 1: I guess my question is what's the max speed/velocity at ...
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Correlation between supermassive black hole properties and galaxy rotation speed

Is there any correlation between the size or spin - or any other properties - of a galaxy's central supermassive black hole and the speed of galaxy rotation (which I think would also be proportional ...
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Question about redshift and effective gravity at the rotating neutron star surface

For a rapidly rotating neutron star, if consider the star as a sphere, redshift at the equator surface will be larger than at the pole. But if consider the star as an obsolate sphereiod (the ellipsoid ...
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Was there ever a meteorite with a measurable gravity?

Did we ever find a meteorite (a meteoroid that has fallen down to Earth) whose mass, density and gravity were high enough to demonstrate their gravity similar to the Cavendish experiment, so that ...
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How does a planet-sized robot standing on a planet affect its gravity? [closed]

I originally asked this at the sci-fi exchange but was told it was off-topic as it was about real-world science. Here is a picture of Unicron standing on top of the planet Cybertron, as written by ...
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Do planets have effect on velocity of Earth?

There is method for finding extrasolar planets called Transit-timing variation. If I understood correctly, exoplanets accelerate or decelerate each other (according on their position), so we can ...
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How small could an orbital system be in our solar system?

Answers to How does the Sun's gravity have so much force and pull on the solar system? How does it scale? Newton's law of gravity scales on orbits so that we can theorize very small orbits with very ...
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How does the Sun's gravity have so much force and pull on the solar system? How does it scale?

Watched this video: https://fb.watch/1U0vCFBr0L/ Ok, so the distances are huge. And the sizes are much different. But I wonder how then the sun keeps the planets etc. orbiting it. If we swap out all ...
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What makes protoplanetary disks start rotating? (Initial energy needed to rotate)

Planets form from a protoplanetary disk that has been rotating around its star. The initial energy that makes them rotate really matters to me. Why did the protoplanetary disk start rotating around ...
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If suddenly “knocked” or perturbed from its orbit, would gravity eventually return the Earth to its original orbit?

If suddenly "knocked" or perturbed from its orbit, would gravity eventually return the Earth to its original orbit? I am curious as to whether this is even possible. It seems to me that ...
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How to resolve confusions on the rubber sheet analogy of the spacetime curvatures?

How to resolve confusions on the rubber sheet analogy of the spacetime curvatures? I am a newbie to spacetime curvature. I have watched several youtube videos on Einsteins GR and spacetime curvature ...
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Gravity on Mercury's highest elevation?

This post answers what is Mars' gravity at its highest point (Olympus Mons) compared to the Earth's and Mars' standard, it's 0.3736 g (Mars standard is 0.3794 g). This also seems to be the lowest ...
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Does Einstein's theory of gravity say anything about the direction of space [closed]

Why is every representation of Einstein's theory of gravity depicted like this: and not like this: And many other ways it can be depicted. They suggest that the fabric of space-time is a flat plane
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Intuition about why gravity is inversely proportional to exactly square of distance between objects

What is the intuition behind why gravity is inversely proportional to exactly square of distance between two object and not cube or not some multiplier. Basically how Newton came up that its exactly ...
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What are “non-Keplerian” orbits? What are some familiar examples in our solar system, and can some still be closed?

This excellent answer to Forms of stellar orbits around the galactic center invokes the following concepts: non-Keplerian orbits closed orbits I have a fairly good idea what these mean and so might ...
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By how much does Haumea's fast rotation affect its surface gravity?

The equation for surface gravity is $\frac{GM}{r^2}$ but I'm not sure how to include the effects from its rotation.
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Could it have been possible for the Moon to be split without any observable effect on Earth?

Before asking my question, I'd like to clarify why I'm asking about something so absurd. A supersitious claim has been bought to me that in the past, the moon was split and seperated as a sign. My ...
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The possibility of rapidly changing the Earths orbit via a passing astronomical object

I assume that the Earth could be “gently” (without colossal tidal or volcanic catastrophe) displaced by a passing extra solar star, brown dwarf or planet and end up perhaps 10% further away from the ...
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Is a literal instance of Russell's teapot possible?

Much has been said about Russell's teapot, and I accept as obvious that a teapot would be too small to be detectable in an orbit around the Sun by any reasonable method today, or by any method that ...
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Do the Bullet Cluster remnants prove that dark matter consists out of particles?

Some time ago the remnants of a collision between two collections of stars were discovered. These remnants are called the Bullet Cluster: The color blue (non-visible in reality) represents the ...
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How is it possible that Saturn's gravitational acceleration felt by Mimas is stronger than Mimas' own surface gravity?

The surface gravity on Mimas is $≈ 0.063\text{ m}/\text{s}^2$ and Saturn's gravitational acceleration at the distance of Mimas' orbit is: $$\frac{{GM}}{{r}^2} = \frac{{6.674 \times 10^{-11} \times 568....
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Why does time pass faster in moon than the earth?

One of my friends said that, time passes faster in moon than the earth Why does time pass faster on the moon than on the earth?
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Can two heavy objects circling around their C.M. be separated because of the speed of gravity?

Imagine two massive objects, with the same mass (M) circling around their center of mass (C.M.). Let's assume that the distance between them is 1 light hour. Don´t the two bodies get accelerated and ...
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Instantaneous gravity in equation of motion for ephemerides calculation

The equation of motion used for the calculation of orbits of solar system objects (Eq(27) in https://ipnpr.jpl.nasa.gov/progress_report/42-196/196C.pdf ) is formulated in terms of instantaneous ...
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What is 'surface acceleration' of a planet or other body? As opposed to its 'g' (gravity)?

The Mars Fact Sheet at NASA (their NSSDC or NSSDCA section, whatever that means) lists a value for 'surface acceleration' just below one for 'surface gravity'. They also have the values for Earth, ...
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How to find the mass of a planet not knowing the gravitational constant?

So I found this problem, I know the gravity of earth $g_0$, I found the orbital speed of one satellite using this equation $\frac{GM_em_s}{(R_e+h)^2}=m_sa$ ($M_e$ is the mass of earth, $m_s$ is the ...
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Impact on the rest of the solar system if Mercury or Venus were disassembled?

I've watched a few theoretical videos about Dyson spheres where they mention that the most practical way to do that would be to disassemble a planet - preferably one already close to the sun - Mercury ...
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Gravitational waves and gamma ray burst: how were the error bars determined for this speed of gravity calculation? Was $H_0$ used?

This newly updated answer to How precise are the observational measurements for the speed of gravity? and this answer to How is the most accurate value of 𝐺 measured? cites the November 2017 arXiv ...
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If the Sun disappears right now, when the absence of its gravity affects on Earth? [duplicate]

Imagine if the Sun disappears right now. When the Earth will be affected by its absence? Does it affect immediately, or it takes almost 8 minutes? (The time that light travels from the Sun to the ...
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Have I nearly found the event horizon of a black hole?

The calculator on the website https://planetcalc.com/1758/ cites Wikipedia's Gravitational acceleration and implements: $$g = G \frac{M}{(R + h)^2}$$ For a black hole with mass $M$ equal to 5 solar ...
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Why are stars still distant from one another? [duplicate]

Why are stars so far from each other? Shouldn't gravity pull them closer over time? And if the effects of gravity are negligible is there an explanation why stars have to be so distant from one ...
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Kinetic energy and galaxy arm rotation rate

The higher than expected rotational velocity of stars and gas clouds in the outskirts of galaxies is explained today by invoking dark mater that supplies not only the additional gravitational mass, ...

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