Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [newtonian-gravity]

The Newtonian model of gravity in which the force between two objects is given by GMm/r^2.

1
vote
1answer
200 views

Fluid to particles under newtonian gravity

How to start with a perfect fluid concept and reach (by approximations through certain mathematically well defined assumptions) to the concept of particle ? Here newtonian gravitation is being assumed....
2
votes
2answers
543 views

What is an analog to QM's Hilbert space in GR?

I've read that QM operates in a Hilbert space (where the state functions live). I don't know if its meaningful to ask such a question, what are the answers to an analogous questions on GR and ...
2
votes
5answers
5k views

Relation between density and pressure for a perfect fluid

what is the relation between mass density $\rho$ and pressure $P$ for a perfect fluid ?
1
vote
2answers
159 views

Behaviour of mass and momentum distributions under Newtonian Gravity

In the context of this question should mass distribution $\rho(r,t)$ and momentum distribution $p(r,t)$ be well behaved ? By 'well behaved' it is meant that derivatives of all orders exist everywhere. ...
0
votes
3answers
215 views

Evolution of mass and velocity distributions under newtonian gravitation

Let $\rho(r,t)$ and $v(r,t)$ be mass and velocity distributions. Given $\rho(r,0)$ and $v(r,0)$ (initial conditions) what is the differential equation that describes the evolution of $\rho(r,t)$ and $...
35
votes
2answers
3k views

The Impossibility ( or Possibility) of Solving $N$-Body Problem

One can obtain the solution to a $2$-Body problem analytically. However, I understand that obtaining a general solution to a $N$-body problem is impossible. Is there a proof somewhere that shows this ...
9
votes
6answers
3k views

Escape velocity from long ladder

The escape velocity of earth is roughly $11 kms^{-1}$. However, what if a long ladder was built extending out of Earth's atmosphere and considerably more. Then if something was to climb up at much ...
91
votes
10answers
12k views

How can I stand on the ground? EM or/and Pauli?

There is this famous example about the order difference between gravitational force and EM force. All the gravitational force of Earth is just countered by the electromagnetic force between the ...
6
votes
2answers
875 views

How about an exact solution for the position of a planet as a function of time?

Recently I was surprised to discover that no exact solution for the position of a planet as a function of time exists. I am referring to the two-body problem in a gravitational field where Newtons law ...
20
votes
3answers
5k views

Gravity on a doughnut-shaped/Möbius planet

How different would the effects of gravity be if the planet we're on is in the shape of a torus (doughnut-shaped)? For an (approximately) spherical planet, it's slightly clear that objects would tend ...
18
votes
4answers
4k views

How can I measure the mass of the Earth at home?

How can I measure the mass of the Earth at home? How was the mass of the Earth first measured?
20
votes
9answers
15k views

Would it help if you jump inside a free falling elevator?

Imagine you're trapped inside a free falling elevator. Would you decrease your impact impulse by jumping during the fall? When?
15
votes
12answers
3k views

Is the distance between the Sun and the Earth increasing?

$M$ = mass of the Sun $m$ = mass of the Earth $r$ = distance between the Earth and the Sun The sun is converting mass into energy by nuclear fusion. $$F = \frac{GMm}{r^2} = \frac{mv^2}{r} \...
12
votes
8answers
24k views

Is gravity a force and if so what is its opposite?

For every force there is an equal force in the opposite direction on another body, correct? So when the Suns gravity acts on Earth where is the opposite and equal force? I also have the same ...
19
votes
6answers
5k views

Is Newton's Law of Gravity consistent with General Relativity?

By 'Newton's Law of Gravity', I am referring to The magnitude of the force of gravity is proportional to the product of the mass of the two objects and inversely proportional to their distance ...