Questions tagged [newtonian-gravity]
This tag is for questions regarding the Newtonian model of gravity in which the force between two objects is given by $~GMm/r^2~.$ It is a natural phenomenon by which all things with mass or energy – including planets, stars, galaxies, and even light – attract one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides.
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Issue while understanding gravity/radius of earth graph [closed]
I have following question.
What are my opinions?
1. Option 1 - This is incorrect. I think dotted line in option 1 from bottom to peak represents center to surface of earth. After the peak, line ...
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Confusion in definition of Potential Energy
Potential energy is defined like this. $ΔP.E=-W_{AB}$. This means that the potential energy at point A minus potential energy at point B should equal the negative of the work done by a conservative ...
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Gravitational potential energy in Escape Velocity
From the derivation of formula of Escape Velocity we know that
Minimum kinetic energy = Gravitational Potential Energy
But in this circumstance, isn't it the value of gravitational potential energy ...
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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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Electromagnetism in the Cavendish experiment [closed]
What are the best arguments that debunks the idea that the attraction between the masses observed in the Cavendish experiment is caused by electromagnetism, and not gravity?
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What would happen if I was swimming in a pool that fell several stories? [closed]
What forces would I be subjected to (and is there a depth at which I would likely survive), if I was swimming in a 12' pool at the top of a ten story building and the whole pool fell through the floor ...
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Question on Gravity (Ring and Sphere) from JEE Mains 2021 [closed]
Find the gravitational force of attraction between the ring and sphere as shown in the diagram, where the plane of the ring is perpendicular to the line joining the centres. If $R\sqrt8$ is the ...
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Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?
If, in free space, I throw two objects towards each other, they can either miss each other and fly apart (if the velocity is enough and there's not enough gravitational attraction between them), or ...
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Debunking flat earther's about Cavendish [closed]
Yes, I know it's useless to waste time with this kind of people because they will never accept reality, but I learn a lot from these types of discussions, so here it goes. Flat-earthers deny all ...
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Does this question require any calculus to solve? [closed]
So, I came across this question in a book,
Two spherical bodies of mass $M$ and $5M$ and radii $R$ and $2R$, respectively are released in free space with initial separation between their centers ...
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Total energy of a rocket launch
I'm wondering how the total energy of a combined Earth-rocket system is conserved in a rocket launch?
Before launch, kinetic and gravitational potential energy of the rocket are 0. It then launches, ...
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Observation of the effect of gravity on the motion of antimatter
In a recent paper (https://www.nature.com/articles/s41586-023-06527-1), the authors state that
we find that the local gravitational acceleration of antihydrogen is directed towards the Earth and has ...
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Why does gravity cause objects to pull other objects with constant acceleration and not constant force? [duplicate]
I know that this may come off as an incredibly dumb question, but please hear me out for a while.
Why don't objects just tug at other bodies with a constant force? Instead, why do they apply ...
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Sign of force for assumed $mgy$ gravity [closed]
If gravity force of earth is $mg$:
if positive y is pointing upwards, then: $m\vec a = -mg\hat y$ and
$\ddot y = -g$
if positive y is pointing down, then: $m\vec a = mg\hat y$ and $\ddot y = g$
If ...
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Electric constant and the Cavendish experiment [closed]
If I did the Cavendish experiment but accidentally used magnetic materials or materials that interacted electrically in some way, would I arrive at the result of the electrical constant, the ...
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Escape velocity work done problem [closed]
We derive the formula of escape velocity by using conservation of mechanical energy, where we consider that work done by external force is neglected. But to provide the velocity to send an object to ...
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Can mass be negative? [duplicate]
like charge is fundamental property of matter which exist in both negative and positive aspect and help us to understand the electro-magnetism ,in the same ways would mass be negative ?
in that ...
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What is the smallest known gravitationally bound system?
Recent discovery of a satellite orbiting Dinkinesh made me wonder how fragile that system must be. Based on the numbers and photos given by NASA, I estimate that binding energy of the two bodies is of ...
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Why do gravity and electricity sometimes obey inverse square laws over the same distance scale?
Is this a chance mathematical coincidence or is there a good physical explanation for it?
user381695
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Find the acceleration of a block sliding down on an accelerating inclined place [closed]
I don't understand the solution provided in the image. Using Newton's second law for forces along the x-axis (parallel to the inclined plane), shouldn't the equation be $ma = mg\sin \theta+ mb\cos \...
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Is there a way to express the collisionless boltzmann equation in terms of positions, velocities, times, without the distribution function?
Suppose I have data that represents a field of positions and velocities. If the distribution function (DF) for the data is $f(x,v,t)$, I know that the DF must obey
$$\frac{\partial f}{\partial t} + \...
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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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Which of Newton's shell theorems applies to a galaxy?
From this question I gathered that Newton came up with two sets of shell theorems, one for hollow spheres and one for solid. It was also said we should use the version inside a solid sphere to model ...
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Why was Heaviside perplexed by this property of the gravitational potential?
When reading an article (by Heaviside, linked below), I came across this sentence:
For it must be confessed that the exhaustion of potential energy from
a universal medium is a very unintelligible ...
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Which gravitational differences we would feel if the sun disappeared?
I would like to start by stating that I'm not a physicist, I'm purely a curious individual.
I've been speculating about the differences the loss of the sun's gravitational field would have on us and ...
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3
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Gravitational force and centre of mass
So question goes like
"What is the magnitude of gravitation force of the particle due to rod?"
In the figure the particle is of mass $m$ and from distance $d$ from end of the rod and the ...
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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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Equivalence Principle in Newtonian Physics vs GR: A Thought Experiment
I have a question regarding the equivalence principle as it applies in Newtonian Physics and General Relativity. Consider a thought experiment involving a free-falling elevator.
Inside the elevator, ...
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Active Transformation doubts [closed]
I think the reason of asking the question solely lies in the confusion that different answers cause as they are somehow different answers on the same questions, or not maybe the same.
First ...
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Potential energy with different heights [duplicate]
If system consists of earth and ball and ball is dropped from height $h_i$ to $h_f$, then:
$\Delta U = -(W_{earth} + W_{ball})$ ($W_{ball}$ can be neglected since it's small)
$\Delta U = -(-mg(h_f - ...
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Sun-Earth-Moon-Spacecraft four-body simulation using MATLAB - unexpected results [closed]
I'm trying to simulate this four-body system by directly integrating the system of equations
$$\ddot{\textbf{x}} = \sum_{i=1\:i\neq k}^4 G\frac{m_i}{|\textbf{x}_i-\textbf{x}_k|^3}(\textbf{x}_i-\textbf{...
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What exactly are the 12 conserved quantities in the Two-Body Problem?
The Two-Body problem consists of 6 2nd-order differential equations
\begin{equation}
\ddot{\mathbf{r}}_1 = \frac{1}{m_1}\ \mathbf{F_g} \\
\ddot{\mathbf{r}}_2 = -\ \frac{1}{m_2}\ \mathbf{F_g}
\end{...
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Dynamic equilibrium of planets
We can describe statical equilibrium ( forces, moments ) in a cuboid $$ \Sigma F_x=0,\Sigma F_y=0,\Sigma F_z=0~$$ In dynamics can we describe similar dynamic equilibrium within an inertial ...
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Is there a rigorous proof regarding the non-linear stability of the $L_4$ and $L_5$ Lagrange points?
I have found that many proofs regarding the stability of the $L_4$ and $L_5$ Lagrange points are based on linear approximations of the equations of motion near these points. However, from a dynamical ...
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A body with zero total energy in a conservative field
So imagine a mass $M$ is kept fixed at a point. Another mass $m$ is at rest at infinity. Hence it has net zero energy. Now imagine the mass $m$ starts moving towards $M$ due to the gravitational force....
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What does Newton's Theorem XXXIII in his book "Principia" mean?
If to the several points of a given sphere there tend equal centripetal forces decreasing in a duplicate ratio of the distances from the points; I say, that a corpuscle placed within the sphere is ...
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Toroidal gravitational field from Gauss theorem?
Even if complicated, can the gravitational field of a uniform toroid of radii $R$ and $r$ be calculated with the Gauss theorem? I know that we can guess the gravitational field of a RING but I have ...
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2D newtonian gravitational flux not the same for centered/offset point mass? [closed]
$\alpha*r$" />
I am having trouble comparing the 2-dimensional gravitational flux, due to a point mass $M$ located at the origin of the gaussian circle (in green) at point O, versus a point mass ...
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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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How would the volume of a drop of water on the Moon and other bodies compare to one on Earth? (indoors of course!)
Searching for "volume of a drop of water from an eyedropper", I ran across this answer on Quora:
It depends on the size of the dispensing tip, but generally for a Pasteur pipette it is ...
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Derivation of Kepler's third law using Virial theorem
I am familiar with the long derivation of Kepler's third law using the equations of motion. One starts with
\begin{equation}
\dot{r}=\sqrt{\frac{2}{m}\big[E-V(r)\big]}
\end{equation}
and integrates to ...
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Multidimensional space and Newton's inverse square law deviation [duplicate]
Many times I have heard the physicist Michio Kaku saying that the deviation on Newton's inverse law could demonstrate the existence of multidimensional space, which could support one of the aspect of ...
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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 does gravitational potential energy work in a very large distance?
I have a question that I made up when I was in high school in first year when we started physics and potential energy and something like that. The question goes like this:
Imagine the universe has ...
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Two balls are dropped from the same height. Ball A is metallic and B, made up of an insulating material. Which of them touches ground first? [closed]
General motion under gravity states that both of them reach the ground simultaneously. But here, ball B reaches first. I searched for the solution but couldn't find any. Does it have anything to do ...
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Gravitational potential energy of a galaxy
How can the total gravitational potential energy of a galaxy be calculated?
Lets assume for simplicity that the entire galaxy follows an exponential mass density function for an infinitely small ...
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Nuclear binding energy and gravitation
A nucleus $A$ can be split into two smaller nuclei $B$ and $C$. It is well known that the sum of the masses of $B$ and $C$ will not equal the mass of $A$ due to the nuclear binding energy and the ...
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Newton's 2nd law and gravitational law [duplicate]
I am studying the Newton's Law's of Motion, and really confused about one thing.
I know that bodies of very small mass get attracted to our earth due to a force it exerts, due to its huge mass.
So ...
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Angular velocity in planetary motion
Torque about centre of sun is zero.
$$T=Ia$$
So angular acceleration is zero too, so angular velocity should remain constant.
However it is not the case. Please tell where I went wrong.
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What are the conditions that produce various shapes in 2D motion?
I have read that projectile motion is parabolic in nature. I know that the equation of projectile motion represents a parabola. But when do we get a parabolic curve? Does it happen when there is ...
