Questions tagged [gravity]
Questions regarding the attractive force which exists between any two bodies of matter.
425
questions
2
votes
1answer
89 views
Is it possible make artificial gravitational waves?
Is it possible to generate gravitational waves (creating low or high disturbance in space-time) from very heavy bodies spinning at very high speed artificially?
4
votes
1answer
130 views
Does the gravitational attraction near the surface of dense celestial objects diverge from inverse square?
Does the gravitational attraction near the surface of dense celestial objects (neutron star, white dwarf itc) diverge (to infinity) from inverse square?
This question is inspired by the similarity ...
5
votes
2answers
95 views
How is the gravitational effect of galaxies outside of the visible universe on galaxies within the visible universe currently modeled?
Given currently accepted models of the universe,
How much mass is outside of the visible universe?
What is the gravitational effect of that mass on the visible universe?
The question How strong is ...
1
vote
2answers
129 views
How does energy (from fusion reactions still inside the sun) still have gravitational attraction?
In this answer they say:
While the conversion of mass matter† to energy in the Sun's core now represents a loss of mass proper matter, it turns out that that energy (trapped in the Sun and slowly ...
1
vote
1answer
86 views
Impact verses vacuum
How do asteroids, comets and other stuff stay together when colliding in the empty vacuum of space, when they are made up of non-sticky substances like rock?
My understanding is that the force of ...
1
vote
2answers
108 views
Largest body in the solar system that a baseball thrown by a professional pitcher could escape
What is the largest (most massive) known body in the solar system that a professional pitcher could throw a baseball off of, i.e. that has an escape velocity lower than ~102 MPH? (45.33 m/s)
1
vote
1answer
53 views
Gas Planets composition and gravitational effects
It has been postulated that Gas Giants have a solid core and an obvious gaseous atmosphere. Question: As the gas is a state of matter and gravity draws all matter inward, is the reason the gas is ...
7
votes
3answers
175 views
How does gravity affect a physical clock?
In all the explanations for time dilation and how gravity affects time a common example which is used is "Clock near to the ground will tick away faster than clock away from the ground due to gravity"....
0
votes
1answer
70 views
At what gravity does a body's gravitational lensing become observable?
I wonder whether we know at how much gravitation a gravitational lensing around a celestial body becomes observable (visible in the sense of that we see stars on the wrong places, stars behind the ...
2
votes
1answer
59 views
Can the gravitational potential in a spiral galaxy be positive?
Thinking about this question I wanted to start with a rough model of the average gravitational potential of the Milky way. I ran across D. P. Cox and G. C. Gomez 2002 Analytical Expressions for Spiral ...
2
votes
0answers
42 views
What influence does the Interplanetary Magnetic Field have on Planetary Orbits?
CONTEXT
The equation $F_D=\frac{GMm}{D^2}$ is a standard equation in Newtonian gravitation. It describes the centripetal force exerted, by a source mass$M$, on a target particle of mass $m$ located ...
1
vote
1answer
54 views
How does the surface gravity on Mars vary between the equator and its poles?
A day on Mars is similar in length to the Earth's day. On Earth, due to rotation, the surface gravity varies from 9.78 m/s² (0.997 g) on the equator to 9.832 m/s² (1.003 g) on the poles. I wonder how ...
6
votes
1answer
88 views
Gravitational field for oblate spheroid?
Consider a planet, described as an oblate spheroid. Assume that the spheroid is uniformly dense but not a point source. Outside of the object, do all vectors in the gravity field point through a ...
0
votes
0answers
60 views
can gravity be faster than light in some specific cases? [duplicate]
This is a follow up question from
If an event occurs at a point in space time what will an observer experience first, it's gravity or the light from it?
This https://en.wikipedia.org/wiki/...
4
votes
1answer
97 views
If an event occurs at a point in space time what will an observer experience first, it's gravity or the light from it?
Let's assume a person is close enough to an object in space time to be able to observe it's gravitational effects and the light coming from it.
If that object suddenly pops out of existence (...
22
votes
2answers
3k views
What observation can be expected on LIGO if any when Betelgeuse goes supernova?
What observation can be expected from the LIGO† gravitational wave observatory if any when Betelgeuse goes supernova?
Could we know that Betelgeuse has gone supernova before we see it light up our ...
0
votes
6answers
164 views
Would planet explode without gravity?
A planet (as well as a dwarf planet) must, according to the IAU definition, have sufficient mass to assume hydrostatic equilibrium (a nearly round shape). Does it mean they would break apart or ...
0
votes
0answers
21 views
A question about stress energy tensor at junction surface
I am now reading a paper (whole paper link)which regarding construct a worm hole by cutting off the stress energy tensor and glue interior and exterior space at $r=a$. ‘Nevertheless, I am confused ...
18
votes
1answer
5k views
Moon's unusual gravity
We know that the Moon's gravity is about one-sixth that of Earth. Then I recently read that the mass of the Moon is about one-eightieth the mass of Earth. Since gravity depends on the mass of the 2 ...
4
votes
0answers
93 views
How do I calculate the Hill radius of a star in a binary system?
Is there an easy way to calculate the Hill radius of a star in a binary system at different orbital radii where both stars are of the same mass and in circular orbit around one another’s centre of ...
1
vote
0answers
23 views
Doppler Shift Vs Gravity Assist for Frequency Shifts from Rotating Galaxies
Frequency Shift of Light Leaving Rotating Galaxies:
Differences in Doppler Shift due to Radial Velocity
Vs
Frequency Shift due to Gravity Assist from a Rotating Galaxy
A description of estimating ...
15
votes
1answer
287 views
A Sky Map of Gravity - what would it look like?
PREAMBLE
Sky Maps exist which show the distribution and intensity of electromagnetic radiation received on Earth at various wavelengths. An obvious form is a map of the stars (Star Chart).
Maps ...
11
votes
4answers
9k views
Is Earth's Surface “In orbit”?
I'm having trouble understanding relative angular/tangential speeds at increasing altitudes above Earth's surface. In particular, I find this comparison of tangential velocities on Wikipedia very ...
2
votes
2answers
88 views
How to determine the orbital period of an asteroid using Kepler laws given its orbit's radius?
Given that the mean distance of an asteroid from the Sun is $450 \times 10^6$ km is it possible that the asteroid completes one rotation around the Sun in two years?
According to the third law of ...
5
votes
1answer
89 views
Can we use Breakthrough Starshot spacecraft to detect any unknown massive object in our solar system?
For example, the hypothetical Planet Nine.
Since we just want to prove or rule out the existence of Planet Nine in our solar system, we can avoid most of the technical challenges for StarChip (camera ...
8
votes
2answers
2k views
Gravitational Properties of Asteroids
How large would an asteroid have to be in order to hold a person so that the person could not escape?
1
vote
0answers
66 views
Rocket Equation from Newton’s 3rd Law, Force of Gravitation, and dp/dt [closed]
I am using the derivative of momentum (dp/dt) with Newton’s 3rd Law with the gravitational force of Earth.
$$
F - F_{gravity} = \dfrac{\mathrm{d}p}{\mathrm{d}t} \\
F - \dfrac{G \, m_e \, m_r}{...
2
votes
1answer
78 views
How is Earth's gravity modelled?
The Earth does not have a defined geometric shape. Then how do space scientists who want to put a satellite in orbit model the gravitational field of Earth? Do they assume a single object with minute ...
1
vote
2answers
86 views
Does the Lagrange L1 point have a 'size'?
Like in cubic kilometers, what is the size of L1 "area of influence"? being unstable I guess that size can vary?
1
vote
2answers
216 views
How much volume of gases could be added to Mars atmosphere that the planet gravity can retain?
This article Mars atmosphere states that
Today Mars atmosphere is very thin, but it was not always like this. Around 3.5 billion years ago, the red planet had a thick enough atmosphere for liquid ...
3
votes
1answer
101 views
Where would an object fly to if it were to leave the gravitational field of Earth? And would it stop somewhere? What would happen to it?
My 3,5 year old son is asking :-) He can take answers for a 15 yo I think. Many thanks for your help!
2
votes
2answers
108 views
The dominance of Gravity vs Strength and its dependency on crater size
So I am trying to write a research paper (about 3700 words) for high school about the topic "The dominance of Gravity vs Strength and its dependency on crater size" or something similar.
I have ...
13
votes
2answers
4k views
How does the Moon's gravity affect Earth's oceans despite Earth's stronger gravitational pull?
Given that Earth has a much stronger gravitational pull than the Moon, how does the Moon have any influence on Earth's oceans?
5
votes
1answer
138 views
Have more recent LIGO/VIRGO gravitational wave measurements narrowed down the speed of gravity further?
This answer to How precise are the observational measurements for the speed of gravity? says:
...in 2013 a Chinese group built a model using Earth's tides that helped them narrow it down.
...
1
vote
1answer
150 views
Do gravitationally bound (e.g. orbiting) objects really resist the expansion of space?
Thinking about the expansion of space, it is commonly explained that gravitationally bound objects (like galaxies and galaxy clusters) will not be affected by the expansion of space (dark energy). I ...
0
votes
2answers
105 views
Black hole's gravity
Is gravity relative to volume, or size of an object?
Since a black hole is a massive star that collapses on its weight, how comes the same sun's mass, when it becomes a black hole, provides gravity ...
2
votes
1answer
2k views
Could the rotation of a black hole cause other planets to rotate?
Because everything rotates so perfectly, and we know that some blackholes rotate and they're the biggest things in the universe, so a silly question comes to mind.
If you remove all black holes from ...
0
votes
0answers
27 views
Why aren't globular clusters disk-shaped? [duplicate]
I thought that solar systems and galaxies are disk-shaped because that is the most stable shape under gravitation. Globular clusters are very old, often times older than their host galaxies, so why ...
16
votes
1answer
2k views
Why can't supermassive black holes merge? (or can they?)
The CNet article Astronomers discover two supermassive black holes in a death spiral links to Discovery of a Close-separation Binary Quasar at the Heart of a z ~ 0.2 Merging Galaxy and Its ...
1
vote
3answers
93 views
What effect does Earth losing a part of its mass have, is there an impact on the Earth's orbit around the Sun?
This is a random question that popped into my mind. I'm not a physicist or astronomist, however, I am genuinely curious. Also, this is not intended as a science fiction question, but an actual science ...
-2
votes
1answer
138 views
Wormholes man made are real? [closed]
Can we bend two points of spacetime in a way we would create a wormhole ?Why havent we tried it yet?How much energy would we need to do it?
5
votes
2answers
123 views
If I could see from a Gravitational-Time dilated place to somewhere far which is not dilated, would I see fast moving people?
Gravitational time dilation like the one shown in the movie Interstellar, causes time to move slowly for someone within the high gravity reference frame. Now let's say that from such a place, I was ...
6
votes
4answers
6k views
Why do things float in space, though the gravity of our star is always present? [closed]
In the solar system, things float around. We are so certain that the gravity of our sun exists. Still, why does that gravity not influence satellites and other objects there?
Our solar system is also ...
23
votes
4answers
11k views
Why can't we feel the Earth's revolution?
I googled it and checked a few Q&A and there's only things about "Earth's rotation". But why can't we feel the revolution?
They say we can't feel the rotation because the Earth spins at a ...
0
votes
1answer
70 views
If a solar system were surrounded by a cloud of debris, is it possible for a planet's orbit to intersect it?
I'm doing research for a story that I'm writing and I'd like some physics advice on whether a hypothetical system of celestial bodies is possible.
Suppose the following:
A system of planets orbiting ...
20
votes
3answers
6k views
Can a magnetic field of an object be stronger than its gravity?
Can a planet, star or otherwise have a magnetic field that is stronger or have more range than its gravity?
49
votes
3answers
16k views
If a massive object like Jupiter flew past the Earth how close would it need to come to pull people off of the surface?
I understand this is a silly hypothetical but I'm asking for a 7 year old so please bear with me.
Imagine an interstellar stray gas giant comes flying through our solar system.
If we were not ...
4
votes
3answers
299 views
Can a black hole “supernova”?
In layman terms:
nothing ever escapes the pull of a black hole, not even light
when a super massive star reaches the end of it's life you get a supernova
sometimes the "remains" of these stars can ...
-1
votes
2answers
70 views
Planets may repel each other in few cases
We know that when two huge black holes collide they produces gravitational waves in space time curvature. So if I am not wrong another object in space if goes in that direction during production of ...
31
votes
2answers
6k views
Are black holes spherical during merger?
I've been thinking about black holes, specifically during the final moments before two merge. I'm wondering if black holes, or I guess more specifically their event horizons, are always spherical. ...
