Gravity is an attractive force that affects and is effected by all mass and - in general relativity - energy, pressure and stress. Prefer newtonian-gravity or general-relativity if sensible.

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Spaghettification while still in orbit

THIS POST does a pretty good job of giving an idea as to what the differences in forces becomes as you approach a black hole. For a small enough black hole, you would reach the dangerous tidal force ...
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Is gravitational acceleration less affected by relativistic mass increase? [duplicate]

Acceleration due to mechanical force will lessen due to relativistic mass increase as kinetic energy becomes significant near c. But if acceleration is gravitational, the gain in relativistic mass ...
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Leading-order cause of diurnal (not semidiurnal) variations in $g$?

The following graph shows the result of a very impressive differential measurement of the gravitational field in Boulder, Colorado, over a period of a couple of days. Floris got it from a ...
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When/Where will the planets colide?

Given N bodies of known position, mass, speed and direction, if they were to collide, where it will happen and when? PS: this is not a homework... im working on a physics simulation engine... ...
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186 views

Variation in measurements of $g$ on the Earth's surface due to the Moon's gravity

A book, Exercises for the Feynman Lectures on Physics, has recently been published. It consists of homework problems to provide practice with the techniques and concepts used in the famous Feynman ...
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Why is there no Gravitational Magnetic Field?

We think that the electric field and gravitational field operate similarly with their corresponding charges/masses. With just a difference that the electric field is sometimes attractive and sometimes ...
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From where comes the raindrop

First off all, I've no knowledge of how all this works. I've only got some common sense of "how things work"... But I've been wondering this for quite a long time now, so maybe you guys can help me. ...
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Is Gravity a part of the Strong Nuclear Force? [duplicate]

In episode 7 season 5 of Through the Wormhole, they say that gravity could just be a manifestation of the strong nuclear force and that the force carrier are a pair of Gluons. Is this valid in anyway? ...
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1answer
79 views

Why do we say that the electric forces are stronger than gravitational forces? [duplicate]

May be I am asking a stupid question but I am very confused...I understand both forces are inversely proportional to the distances squared, and that the gravitational constant is roughly $10^{-20}$ ...
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1answer
82 views

Why point mass leaves it's own gravitational well? [closed]

I suppose that point mass has its own gravitational well. Why this point mass is still attracted by other gravitational waves. I expect that this point mass is surrounded by "gravitational hills". Why ...
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78 views

Why does the earth have to feel a pull when something falls?

Heck, I'm not even worried about the speed of a reaction. But remember that if I fall towards the earth, with a force, the earth has the same force exerted upon it in the opposite direction. I was ...
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74 views

Jump from a falling object [duplicate]

There have been quite a few plane crashes the past week and this question popped into my head of which I need a good explanation in science about the possibility of survival or not and why. Assuming ...
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3answers
78 views

Does gravity stack?

If I am standing on a planet on the opposite side from its sun will I feel the downward pull of both the planet's gravity and the star's gravity? In other words, does gravity "stack" (Any D&D ...
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171 views

Space-time curvature creates gravity or is it (could it be) vice-versa too?

Mass (Energy) creates space-time curvature and thus it forms the reason for gravity. Can it be vice-versa too? Like, mass created gravitational field, gravitational field created space-time curvature? ...
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67 views

How does weight add up to press on things?

I think I understand how pressure works with gases. More molecules bouncing around -> more random impacts -> stronger force. But I realized to my embarrassment that I don't understand how solid ...
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2answers
112 views

Frame dragging — is there a “non-tiny” example?

Now. As I understand it, in fact, the earth (10^25 kg) creates a very small, very tiny, frame dragging effect. Indeed, we have measured this using satellite experiments. So, the Earth (10^25 kg) ...
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0answers
64 views

Gravitational atraction of fast object [duplicate]

Let's imagine a asteroid that travels with 0.99999999999999999c. (I know it's impossible). Anyway... Relativistic mass of such object would be almost equal to earth's stationary mass. Now let's ...
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3answers
202 views

Could Dark Matter particles that don't couple to quarks or leptons have been produced?

With what we know about physics, is it possible that when the universe 'began', around when quarks and leptons were produced, another particle, which doesn't couple to either quarks, leptons or ...
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what is this force that is able to surpass an entire planet's force on it?

I have a wet teabag in an empty cup. If I will hold the teabag and touch the wall of cup with it, it will stick to the cup, like there would be glue or some magnetic field, but there's just water. ...
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0answers
41 views

Statistical Mechanics with Gravity [closed]

What complications arise when examining the statistical mechanics of a system under the influence of gravity? Is it significantly different from the classical treatment of statistical mechanics?
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17 views

What's the evidence, if any, for some local concentration(s) of dark matter in some region(s) smaller than a galaxy?

What's the evidence, if any, for some local concentration(s) of dark matter in some region(s) smaller than a galaxy? Galactic-sized--or larger--gravitating halos seem to get all the attention. I'm ...
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0answers
74 views

Is inertia actually a property of the force rather than the mass?

I ask this because it occurred to me that the inertial property of mass only actually arises in the context of forces (such as the EM force) as a resistance to their accelerating effect. Inertia plays ...
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2answers
83 views

Add weight in front or behind the moving wheel?

Consider a wheel with bearing and axle bar rolling on level ground. If I want to help the wheel continue moving longer(or faster speed), should I add weight by moving the rider body in front or ...
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24 views

Do we feel the full force of the earths gravity even though the earth is spinning [duplicate]

As far as I know, since the earth is spinning, centrifugal force should be throwing you off the earth. However, gravity counteracts that by being a stronger force. So if you stood an object with the ...
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1answer
84 views

If dark energy is accelerating the expansion of the universe, why can't I feel it?

Based on the Lambda-CDM cosmological model, our universe is not only expanding, but is accelerating in its expansion. However, the Equivalence Principle would suggest that inertia manifests itself in ...
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2answers
71 views

Dark energy vs. gravity

If dark energy is everywhere around us, then why don't we get separated? For example why don't I get separated from the pen kept in front of me? Or take a similar example in free space. Is dark ...
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1answer
76 views

how does a lizard walk on vertical walls? [duplicate]

One day I was observing a lizard walking on walls as easily as we walk on horizontal surfaces. I got curious to know the physics behind this but I couldn't get to any useful conclusion. I tried to ...
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32 views

What effects would we see on Earth if one star of a distant binary system went supernova?

Assume that astronomers on Earth have been monitoring a distant binary star system for a long time (relative to the orbital periods of the binary system) and then they see one star go supernova. Let ...
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1answer
93 views

Loss of gravitational potential energy in an infinitely far object

Now consider I went into a rocket which goes an infinite distance far from earth. By infinite I mean very far. The gravitational attraction between me and the earth will significantly decrease and ...
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2answers
110 views

What's wrong with my calculation of gravitational potential for a uniform sphere?

This is really embarrassing, but I'm not quite sure where I'm going wrong here... Why is this calculation of the gravitational potential inside a sphere with uniform mass distribution incorrect? ...
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1answer
64 views

Black holes attracting each other [closed]

I was watching the tv series called, through the wormhole, and they mentioned a theory about multiple universes that are separated by a very small distance, like parallel membranes. They mentioned ...
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1answer
53 views

Do objects in free-fall contribute to earth's weight as a whole still?

If everything in earth's atmosphere contributes to earth's overall weight, including air etc. Does an objects weight in free-fall effect this overall weight in anyway. Just say the weight of earth ...
3
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1answer
61 views

Do alternate theories for Dark Matter (like MOND) explain it's effect on gravitational lensing?

For a long time, I was sceptical about the evidence for dark matter. To me, it seemed like a pretty big leap to make when we have no idea whether or not our current models of gravity should apply ...
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2answers
84 views

How do we know gravity isn't acceleration? [closed]

If an accelerometer sitting at rest on the earths surface measures 1 G of acceleration upward. How do we know "space" (the reference) isn't rushing down into the earth. I mean experimentally that's ...
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94 views

What predictions can a quantum gravity theory make?

Some of the major challenges that heralded the need for quantum mechanics we're explaining the photo-electric effect, the double-slit experiment, and electrons behavior in semi conductors. What are ...
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2answers
85 views

What would be walking speed in low gravity?

In $1g$ the average adult human walks 4-5 km in an hour. How fast would such a human walk in a low gravity environment such as on the Moon $(0.17g)$ or Titan $(0.14g)$? Let's ignore the effects of ...
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Capillary action column height in a tube fitted inside another tube?

I was thinking about how would capillary action change in a tube (classic example) and in a tube fitted inside another tube (considering water as the liquid involved). Height of liquid column: ...
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1answer
55 views

How do objects outside a spacecraft fall “around” the earth?

Now I get what microgravity is, how spacecrafts (even moon) fall around the earth to keep up themselves in their orbits and other related concepts after reading ...
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1answer
99 views

Why Does Gravity Work? [closed]

I'm trying to work out if energy has gravity, because if it does, then it will all get sucked into black holes, including dark energy, meaning that there will be no pushing effect left, and that the ...
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1answer
79 views

Gravitational Force (conceptual) [duplicate]

Why is gravitational force always an attractive force? And is the Newtonian formula of gravitational force applicable for very small particles like electrons and protons etc.? From Formula of ...
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2answers
69 views

Will two perpendicular orbits settle into a disc?

Scenario: one "fixed" object (like the sun...) of mass X two "planets" (P1 and P2) of mass Y P1's orbit is perpendicular to P2's orbit, and the sun is the center of both orbits P1 and P2 will never ...
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90 views

Dragon Ball Z: Hyperbolic Time Chamber *(also increased gravity training) [closed]

Firstly, I am sorry if this seems like a joke. It is not. I have always loved the Dragon Ball series, so this question has been on my mind for a while. Can ...
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1answer
37 views

Are galaxies “disk” shaped?

When you look a sphere from a fixed observation point, you can easily mistake it for a circle, so I was wondering: are galaxies really "disk" shaped or we just don't have the means to detect the ...
4
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4answers
477 views

Light and Gravity - bending of light around a massive body [duplicate]

Well, as I have read, a massive body can cause light to bend around itself due to its gravitational attraction. What I don't understand is how, as the Newtonian formula for the force of gravitational ...
3
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1answer
152 views

Black hole thermodynamics in a time dependent metric

For a time dependent space time metric, to get the thermodynamics, does the standard procedure of Wick rotating the time, and then calculating the free energy, work ?
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4answers
136 views

How does gravity slow light without an equal and opposite action? [closed]

This is regarding the gravity well sort of explanation. People claim that gravity doesn't slow light by saying it curves the road by which it travels but if space is indeed without properties and ...
9
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3answers
424 views

“Weakness” of gravitational force

I often hear that gravitational force is much "weaker" than electroweak and strong forces. But how can you compare the strength of interactions without the parameters like mass, charge on which it ...
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0answers
35 views

Are particles with gravitomagnetic charge possible or excluded? [duplicate]

Are particles with a sole gravitomagnetic charge (gravitomagnetic monopoles) possible? Does the theory exclude this possibility? Were there attempts to find such particles, similar to the search for ...
8
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2answers
127 views

Why does angular momentum shorten the Schwarzschild Radius of a black hole?

Angular momentum causes the event horizon of a black hole to recede. At maximum angular momentum, $J=GM^2/c$, the Schwarzschild radius is half of what it would be if the black hole wasn't spinning. ...
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2answers
258 views

gravitational waves and inflation theory

I am not a technical guy and I have no scientific knowloedge in physics but I have been reading books, watching videos in order to understand our cosmology and ...