Questions tagged [orbital-motion]
The path a body takes while moving through space under the influence of the gravitational forces of other bodies
2,525
questions
1
vote
1
answer
301
views
Potential Energy for Non-conservative Forces
I was studying for the GRE and came across the problem below.
A small puck of mass $M$ is attached to a massless string that drops through a hole in a platform, as shown in the diagram above. The ...
CommunityBot
- 1
20
votes
3
answers
1k
views
Can perfectly stable orbits exist in GR?
Defining "stable orbit" between two bodies as one where, in the absence of other bodies or non-gravitational forces, the distance stays between some value pair $r_{min}>0$ and $r_{max}$. ...
- 355
3
votes
1
answer
503
views
How accurate does the ISS's velocity and altitude need to be to maintain orbit?
We know the the ISS is not drifting weightless in space, but rather is constantly falling as it circles the Earth. To do this it must be at a specific altitude and moving with a specific velocity. ...
- 689
0
votes
2
answers
82
views
What would happen to the moon's orbit if we reduce (instantaneously) its mass? [closed]
In my opinion the moon's orbit shouldn't change, because an orbiting body is a free falling object and the trajectory of a free falling object is not affected by its mass (because the inertial mass ...
- 207k
4
votes
5
answers
1k
views
The validity of the Longitude of Perihelion
As I understand it from Astronomical Algorithms, by Jean Meeus, the Longitude of Perihelion is a very common numeric value associated with planets, even used as one of the planetary orbital elements. ...
- 1
3
votes
3
answers
555
views
Why does atmospheric drag speed up satellites?
I've read that old satellites slowly lose altitude when encountering the very thin atmosphere, and strangely enough they speed up. My theory is that the work done by the drag force is insignificant in ...
- 936
1
vote
2
answers
147
views
Doubt on conservation of angular momentum for Kepler's laws
Just before proving Kepler's laws, my Professor claimed that if $\vec{F}$ is a central force with center $O$ and it is the only force acting on a point $P$, then the trajectory of $P$ is a curve plane....
- 13
1
vote
0
answers
62
views
Why does a moon's orbit get more circular with time?
I understand that there is a transfer of energy between a moon and a planet depending on whether the moon is orbiting faster or slower than the spin rate of the planet. This would obviously change the ...
- 207k
1
vote
1
answer
386
views
How can I obtain the position of the Earth on the orbit for given date?
I would like to be able calculate (or at least download some time-series data of) the position of the Earth on it's orbit at given date. For my purposes, it would be sufficient to account for the ...
CommunityBot
- 1
0
votes
1
answer
269
views
Derivation of the equation of a hyperbolic orbit from the conic section expression derived via the orbit equation
So I'm looking to derive the equation of a hyperbolic orbit from the general expression for a conic section $$r=\frac{l}{e\cos\theta+1}$$ that you get out of solving the orbit equation for an inverse-...
CommunityBot
- 1
0
votes
1
answer
62
views
Has our knowledge of astrophysics and gravity reached the point where we can accurately calculate Lagrange points?
is it possible for us today given the knowledge we possess of gravity and our success with inserting satellites in to steady/ geosynchronous orbit and any knowledge we have on the relative size (and ...
- 207k
2
votes
1
answer
88
views
Are we certain of the mass we calculate for supermassive black holes?
If astronomers have concluded that the rotation speed of objects held firmly within a galaxy but far from a galactic center is too great to be explained by the visible matter of the galaxy alone, what ...
- 207k
0
votes
3
answers
579
views
Two particles rotating about their center of mass
Two bodies each of mass $m$ are rotating about their center of mass where the radius is $r$.
Here centripetal force of each body is $\frac{mv^2}{r}$ where $v$ is the linear speed. Now, gravitational ...
- 67
1
vote
2
answers
97
views
How can it be known what the Earths periods of eccentricity, perihelion and obliquity are when the observational data only cover at most 3,000 years?
How can it really be known what the earths periods of eccentricity, perihelion and obliquity are when the observational data only cover at most 3,000 years? What I mean is that these parameters ...
- 21
3
votes
1
answer
225
views
Geodesic equations and Carter constant: how can I derive the right equations?
Introduction
Suppose the Hamilton-Jacobi equation:
$$\frac{\partial S}{\partial \lambda} + \frac{1}{2}g^{\mu\nu}\frac{\partial S}{\partial x^{\mu}}\frac{\partial S}{\partial x^{\nu}}= 0. \tag{1}$$
Now,...
CommunityBot
- 1