All Questions
Tagged with newtonian-gravity gravity
404
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How much time does it take for an object to fall from space? [closed]
Let's say there's an object of mass $m$ in space, $h$ meters away from the surface of the Earth. $h$ is large enough that $g$ cannot be assumed to be constant. The acceleration varies according to ...
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0
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31
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Better equations for modeling and simulating a halo orbit?
I'm trying to model a halo orbit at low altitude (10m from surface). The satellite is using propulsion to trace the circular halo path. It looks like this "from the top" (the blue ball is ...
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When is it appropriate to say Newtonian gravity is a force? When is it not appropiate? [closed]
Please help me understand the notion of force when it is applied to Newtonian gravity. From my understanding forces in physics involve interactions with at least 2 objects and can cause an ...
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Dual of Newtonian gravitational field
In the static state, the laws of Newtonian gravity and Coulomb force have exactly same formulas,
$$F = K \frac{A_1A_2}{r^2}.$$
In the electrical case, moving materials produce a field, say a dual ...
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Einstein's equation of gravitation field [duplicate]
I'm looking for the reason why there is the number eight $8$ at the r.h.s. of EI:
$$R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}=\frac{8\pi G}{c^2}T_{\mu\nu}.$$
My attempt was to take the limit of this equation ...
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Gravitational potential due to arbitrary shape
Outside the uniform sphere, the potential is expressed as if all the masses are concentrated in the center of the sphere.
Is it also true for arbitrary shape?
That is, outside any body, is potential ...
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How does gravity act and propagate in a 2+1D universe?—Newtonian versus general relativity
In a hypothetical 2+1D universe:
if we apply the Newtonian concept of gravity, we might expect that the gravitational force between two mass points with a distance of $r$ would diminish linearly with ...
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References on Newton-Cartan Gravity
I'm interested in learning a bit about Newton-Cartan gravity, and I would like some references on the topic. I am already familiar with differential geometry and general relativity, so those could be ...
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Understanding conservation of angular momentum in relation with rotating objects
Conservation of angular momentum says that the angular momentum of a closed system will not change if there is no external torque applied to the system. For example, let's take the example of a ...
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Physical relevance of the $ij$ components of the Einstein field equations in the Newtonian limit
In the weak field limit of general relativity (with matter described by a perfect fluid consisting only of dust), we have the following correspondences:
$00$-component of the Einstein field equations ...
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If most of an atom's mass comes from binding energy, why did people think that anti-hydrogen could fall up if antimatter had negative mass?
Antimatter isn't bound by anti-energy, so doesn't that mean that even if elementary antimatter particles had negative mass, the total mass of an anti-atom would still be overwhelmingly positive?
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Negative Energy and Gravity
Why do many science communicators say that negative masses fall upwards? Is it the same in the physics literature that they say that negative masses fall upwards?
In general relativity, things don't ...
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Newtonian approximation for the tidal forces at the event horizon of a black hole
I'm currently working on a problem where I have to calculate the tidal forces a person experiences if their feet touches the Schwartzschild radius and their head is $1.8m$ elevated above the ...
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Trying to understand Gravitational Field
I have learned that gravitational potential is defined as the amount of work done on bringing the mass from infinity to distance r.
But what does that infinity signify in the definition, I mean like ...
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How much kinetic energy would a star in a galaxy have if it fell to the center?
I want to calculate the speed, or equivalently, the kinetic energy of a star, if it had no rotational speed and fell from a given radius to the center of the galaxy.
I assume Newton's shell theorem ...
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Describe the decrease in potential energy if two forces are acting on it one conservative which is greater than other applied by us in opposite dirn [closed]
So imagine this situation.
An object is experiencing two forces, one due to gravity in downward direction and other applied by us in upward direction such that our force is less than gravitational ...
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Contradiction in negative mass interactions according to GR
I quote Sabine Hossenfelder:
Gravitation is a spin-2 interaction. It is straightforward to see that this means that like charges attract and unlike charges repel. The charge of gravity is the mass. ...
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What is the difference between GPE and gravitational self energy in GR?
What is the difference between gravitational potential energy and gravitational self energy in General Relativity? Are they both the same in Newtonian gravity?
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How a force that is always perpendicular to velocity can change the kinetic energy when another force is acting oppposite to velocity? [closed]
When a satellite is revolving around a planet with an orbital velocity in presence of air resistance, the satellite's Kinetic Energy keeps on increasing as it falls down. The resistive force is trying ...
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4
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524
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Interpretation of gravitational waves
A wave has peaks and valleys. I can think of a sine wave as a wave with peaks and valleys.
Now, if gravity is a wave, can we say that gravity would have peaks and valleys, with the valley becoming ...
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2
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What is the gravitational field intensity of a uniformly distributed mass content in Newtonian gravity?
In an infinite universe composed of single point masses which can be simplified as a uniformly distributed mass density, what is the equation for the gravitational field intensity in Newtonian gravity?...
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How to calculate the period of non-circular orbits?
How to calculate the period of non-circular orbits?
By conservation of mechanical energy:
$$
E = -\frac{GMm}{r} + \frac{1}{2}\mu \left ( \dot{r}^2 + r^2 \dot{\theta}^2 \right )
$$
By the conservation ...
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How is when an object moves gravity not effect it ? As Einstein sais?
Experiment:
*a water bottle with a hole . Water is falling from the hole when the bottle is in rest . When the bottle is released and falls , water stops falling as gravity is not doing effect on it . ...
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Is there an equation that is quick to use that calculates gravity around black holes?
Is there an equation the can calculate gravity around black holes but is less time consuming than EFE? I want to find an equation that is simpler/faster than Einstein's Field Equations but can still ...
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Does MOND respect linear superposition of gravitational field intensities?
Does Milgrom's MOND respect linear superposition of gravitational field intensities as Newtonian gravity does?
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2
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119
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Since when did inertial mass and gravitional mass became equal?
If we think about inertial mass and gravitational mass as independent concepts and develop physics then we would know after a while they are only propotional (by precision we have by now). but it seem ...
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Star with quadrupole in binary system violates Newton's 3th law?
Suppose that, in a binary system of two stars, the star A (and only the star A) has a non-zero quadrupole moment $Q_A$. Then, the star B feels the usual gravity force plus an additional force, ...
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Do objects with non-uniform shapes and mass distributions rotate as a result of gravitational attraction?
I was thinking about orbital mechanics this morning and a question arose: do objects with non-uniform shapes and mass distributions rotate as a result of gravitational attraction?
Thinking through the ...
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2
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General relativity when can we approximate to Newtonian gravity?
Lets consider this scenario in deep void of space where other curvatures of large objects are negligible in this case and we bring 2 objects lets say $A$ and $B$.
We give it a force slightly lower ...
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Newton's approximation of 2+1D gravity
I learnt that the curvature tensor in 2+1D spacetime is zero in vacuum. How is it possible to come from there to the Newton's theory in 2D + time, where I guess, the gravitational force law is still ...
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Is Newton-Cartan theory really equivalent to Newton's theory of gravity?
It is often said that Newton-Cartan theory is a reformulation or perhaps a generalization of Newton's theory of gravity, and it is said that (given certain conditions/assumptions) the two theories are ...
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Does a particle which crosses the galaxy straight (not orbiting) suffer MOND's force in MOND theory?
Lets suppose a particle coming from intergalatic space crosses a galaxy. The particle is not rotating the galaxy, so it has no angular velocity or acceleration. The particle is attracted to the galaxy ...
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Does Global Warming play any significant role in increasing velocity of atmospheric gases?
I understand that moon does not have an atmosphere because it's escape velocity is low and atmosphere gases if it had would escaped into vacuum.
I know Earth has a relatively larger value of escape ...
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Current bounds on the value of $g$ for antimatter
In 2011, the ALPHA experiment showed that the gravitational acceleration for antihydrogen was between -65 and 110 times the normal gravitational acceleration. Has there been any improvement on the ...
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6
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Is the gravitational force a phenomenon or a theoretical invention? [closed]
We use to say that gravitational force is a phenomenon. But since the theory of General Relativity replaced Newtonian gravitational force, how is it possible for a phenomenon to be replaced by a ...
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Will antimatter fall upward in a gravitational force field? [duplicate]
A positively charged particle has a force acting along the electric force field. The contrary is true for a negatively charged particle.
Can we apply the same analogy for antimatter and say that ...
2
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1
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337
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Cosmological constant term in Newtonian gravity [duplicate]
Recently, I came across something I found quite interesting on Wikipedia, which is the addition of the cosmological constant to Newtonian gravity. The Wikipedia page (Alternatives to General ...
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The Pioneer Anomaly - A simple interpretation of J.D. Anderson’s paper please
Although many believe the Pioneer anomaly was resolved by Slava Turyshev in 2012. He believed the altered position of P10 was due to the potential thermal recoil effect from the RTG’s (the small ...
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How does relativity explain Newton's apple? [duplicate]
You must have heard the anecdote about the apple falling on Newton's head that led him to come up with the concept of Gravity. A long time later, Einstein upgraded it to the General Theory of ...
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Can the 0 Gravity of a hollow shell be rephrased to "If an object has a gravitational counterpoint net forces become 0"?
So the basic argument as I understand it for gravity inside a hollow shell is all gravitational forces are equal to 0, because they cancel out from the mass on the other side of the shell irrespective ...
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What is the collective nature of gravity? [closed]
My understanding is that gravity is the interaction between all objects with mass. This applies to every single particle that has mass, regardless of size. We know that bodies with very large masses ...
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Would General Relativity work if gravity were not an inverse square law? [duplicate]
I understand that General Relativity explains gravity by framing it as a consequence of the curvature of spacetime rather than as a force. Does this theoretically guarantee that gravity must be an ...
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How do you find the distance between a massive object and its certain gravitational force?
Okay so I know I might've not phrased the question very well so I will give an example to try to make sense of it:
Say we have the moon and a place in space where the moon's gravitational force is 1,...
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Free falling bodies in the absence of external forces
We know that if two balls $B_{1}$ and $B_{2}$ having masses $m_{1}$ and $m_{2}$ respectively and suppose $m_{1}$ is sufficient greater than $m_{2}$. In daily life observation, we see that both the ...
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An object falling from very far would have varying acceleration, how can that be accounted for?
I want to have a function that describes where a falling object is.
Like this one:
h(t) = -g*t²/2
But this one is for the usual close to the surface case, where there is no variation of gravity due to ...
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Do black holes exert infinite forces?
Black holes have infinite mass so according to Newton's law of universal gravitation should exert and infinite amount of gravity force.
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Gravity Differential Equations
I was just messing around with Newton's Law of gravitation, when I had the idea of converting Newton's Law into differential form (more or less like Maxwell's equations).
I did the following:
#1 ...
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How velocity affects different orbits?
Assume a sun with mass $M$ and a planet with mass $m$. Assume at $t_0$ the planet is $r_0$ (distance) away from sun and has an initial velocity of $v_0$. Also, let’s assume the angle between the $r_0$ ...
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Understanding the derivation of the Newtonian limit of GR
I'm having difficulty understanding some of this derivation. The relevant information, as I understand it is:
We've let the lorentzian metric be a perturbation of the minkowski metric:
$$g_{\mu\nu} = \...
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How do you integrate by parts when you have a triple integral?
I'm studying how particles of equal mass behave in a spherical cluster held intact by gravity. I will assume that the mass density $\rho(R)$ of the cluster is a function of the magnitude of the ...
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