The path a body takes while moving through space under the influence of the gravitational forces of other bodies

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0
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2answers
22 views

Circular Orbit in a spherical potential

If we some point mass of mass $M$, in a spherical potential given by $$\Phi(R,z) = \frac{GM}{R},$$ then under what condition would we get a circular orbit, supposing our initial radius from a central ...
-3
votes
4answers
60 views

Is earth continuously changing its orbit size i.e, circumference of the orbit? [on hold]

One year have 365 days, but in leap year we have 366 days. Does that mean earth is continuously change its orbit size for every four years. like . 365.0 -- 365.1 -- 365.2 -- 365.3 -- 365.4 -- 365.5 -- ...
-3
votes
2answers
115 views

Energy of tides: how does the change of spin of a body affect another body through gravity? [duplicate]

There are a few posts here at PSE that explain how the energy of tides comes at the expense of the Moon/Earth angular momentum. There is something that escapes me: how can angular momentum or KE be ...
1
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2answers
55 views

Use of $g$ for centripetal acceleration

I have attached an image above including the question I'm unsure of (part B) In a nutshell, a satellite is orbiting Earth at the surface. Given is $g$ and the radius of the Earth. For part bi) the ...
3
votes
2answers
102 views

What kind of effect would cosmic expansion have on planetary motion or keplerian orbit? [duplicate]

The question is, if two following phenomena are thought to effect to the motion of the planet that orbits a star: Celestial body is pulled by some massive star by ordinary Newtonian gravity: $$ m \...
3
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1answer
55 views

Velocity of satellite to crash into the earth

I was reading through this post today and was very impressed by the response that was given. However, what would have to happen to the velocity in order to collide with the Earth? Velocity of ...
0
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2answers
45 views

When do two point masses orbit or collide? [closed]

Suppose we have a universe containing two point particles with possibly different masses and initial positions/velocities (with respect to some fixed reference frame). Neglecting relativity and ...
-1
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0answers
30 views

How can a polar orbit of a satellite be achieved? [closed]

I mean an orbit in which the satellite is above antarctica on southern hemisphere and above arctic circle in northern hemisphere? I guess it won't be possible to be exactly above the axis but closer ...
0
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1answer
45 views

How do gravitational sling shots work? [duplicate]

How can an object move faster after leaving the gravity of a planet, should a gain in potential energy by moving away from the planet lead to a loss of kinetic energy? Or am I missing something ...
-2
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0answers
42 views

Satellite collides with earth [duplicate]

Suppose we have a satellite in a circular orbit around the earth. We know that the velocity is given by $$v = \sqrt{\frac{GM}{r}}$$ I'm curious as to what conditions on a velocity change would require ...
0
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1answer
22 views

Is the motion of rotation perfectly symmetrical? [duplicate]

Scientifically, can we say that one of these assertions is more "correct" than the other? (philosophically we can say that the first one is more correct because it makes the motion of other planets "...
-2
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0answers
12 views

Newton's law - satellite position (in 2D) for specific moment of time [closed]

I’m trying designate function that calculate satellite position (2 dimensional) for specific moment of time for better understanding Newton's law of gravity. To verify my calculations I created second ...
1
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3answers
60 views

How to calculate transit time for a specific section of an orbit?

I've searched high and low and I haven't been able to find a formula for this. I'm trying to calculate the time it will take to transit through a defined arc length of an elliptical orbit, whose ...
10
votes
2answers
217 views

Charged Accelerometer in Orbit

It is well known that an accelerometer (or any other object for that matter) in a gravitational orbit will register nearly zero acceleration. According to this answer, this is because the object is, ...
1
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0answers
22 views

How does the Giant Impact Hypothesis resolve impulse for orbital insertion?

The Giant Impact Hypothesis describes that Earth's moon was formed from collision between a proto-Earth and another Mars-sized object. This collision ejected mass from the Earth into orbit, whereupon ...
33
votes
7answers
5k views

Why don't we feel the subtle speed change of Earth's elliptical orbit?

Earth's orbit is a slight ellipse, so to conserve momentum its speed increases when it is closest to the Sun. If the speed changes there is an acceleration. If there is an acceleration there is a ...
3
votes
1answer
54 views

Effective Potential in General Relativity

I would like to clarify a concept about the Effective Potential in General Relativity when the kinetic energy term is not unitary. Suppose (in spherical coordinates) one has a generic line element of ...
1
vote
1answer
44 views

Change in gravitational effect between Earth and the Sun

SPOILERS FOR "INDEPENDENCE DAY: RESURGENCE" ABOUND. I just watch ID:R and had a question about a plot point. In the movie, a large alien ship, which looked to be about 10-20 percent the size of Earth ...
3
votes
1answer
64 views

How can an asteroid fall to a planet?

According to the Kepler's first law, the orbit of an asteroid would be an ellipse having the planet at one of the focuses (to a good approximation). Then how come can it ever fall to the planet?
2
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2answers
45 views

Juno probe's speed is in relation to what frame of reference?

When describing the velocity of space probes in general (the Juno probe in particular) what frame of reference is the velocity quoted in? This is in relation to the news of the Juno Satellite ...
46
votes
5answers
7k views

What does the Moon's orbit around the Sun look like?

I'm curious as to what the Moon's orbit around the Sun looks like. If there's an answer, what's the intuition for it? Here are some things I'm assuming when trying to tackle this question: The Moon'...
0
votes
1answer
31 views

Is it possible that an object orbits another object without ever tangenting or crossing its equator?

Imagine Object 1 beeing the earth and object 2 beeing the moon having a orbit around earth, like the yellow line is demonstrating. Could something like this anyhow naturaly as standalone occur? I'd ...
2
votes
1answer
49 views

Maximum Angular Momentum for an orbit in GR

[The reference for this question is the book Gravitation by Misner,Thorne, & Wheeler.] The trajectories of massive particles around a spherically symmetric body is governed by the effective ...
0
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1answer
28 views

How to calculate orbit of a sphere around a bigger one in microgravity?

I don't have any knowledge in physics, but in a world building related question, I need to know how can I calculate the orbit or the distance in each point of the orbit around a spherical object in ...
2
votes
1answer
85 views

Calculate velocity vector in an orbit [closed]

This is a very specific question for a video game that I am the principle developer of. Having calculated the parameters of an elliptical method, I know the following: $G$ = gravitational constant $...
2
votes
1answer
87 views

On the Stability of Circular Orbits

Bertrand's Theorem characterizes the force laws that govern stable circular orbits. It states that the only force laws permissible are the Hooke's Potential and Inverse Square Law. The proof of the ...
0
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0answers
29 views

Why does the inverse square law cause elliptical orbits? [duplicate]

I've seen it printed multiple places, here for example, that the reason orbits are elliptical is because the gravitational law has an inverse square of the radius. Why does this make the orbits ...
1
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0answers
70 views

Confused about the solution to a problem in IPhO 2001

The problem statement is thus. "Assume that M >> m0, so that the ordinary star is basically rotating around the neutron star in a circular orbit of radius r0. Assume that the ordinary star ...
0
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0answers
30 views

Average of the velocity vector along a Keplerian orbit

I would like to show that the average of the velocity vector $\mathbf{v}$ along one Keplerian orbit vanishes, i.e. $$ \frac{1}{2 \pi}\int_{0}^{2 \pi} \!\!\!\! \mathrm{d} M \, \mathbf{v} = \frac{1}{T}\...
5
votes
2answers
146 views

Kepler Orbits: Small Perturbations->Elliptical Orbits

A group of my physics classmates and I have been stuck on this problem. We have tried a few approaches. The problem is to show that a body following a circular orbit, when given a small radial ...
-2
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1answer
53 views

Gravity and angular momentum

When a mass moves towards a bigger mass at a constant velocity, they will be attracted to each other such that the smaller mass will revolve around the bigger mass with the same speed as before. ...
0
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0answers
60 views

Why does a velocity that gives gravity's centripetal acceleration make you stay in orbit?

Explanations of basic orbital mechanics that I can find all go, $$\frac{v_{satellite}^2}{r} = a_c = \frac{F_{gravity}}{M_{planet}} = \frac{(\frac{G M_a M_s}{r^2})}{M_{planet}}$$ , and so you get a ...
0
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0answers
32 views

Heliocentric Cartesian position of moons

I have a working Kepler orbit system that is GPU accelerated to allow precision, speed and parallelism and more importantly allow as many factors as possible in calculation. For various reasons I ...
-3
votes
3answers
112 views

Orbits for dummies [duplicate]

In a certain universe a perfectly spherical, uniformly dense planet is found to be in a stable orbit around a stable star. The rest of the universe is empty space with no silly stuff like dark matter. ...
0
votes
1answer
37 views

Very Basic Circular motion question

I was asked to draw a diagram of the forces acting on a ball in vertical circular motion when it is at a horizontal point. I drew the weight of the ball acting straight down and the centripetal force ...
0
votes
2answers
36 views

Centrifugal force acting on Spacecraft

This Question may sound very naive. Still somebody can explain the basics in simple words. As I understand, when we equate the centrifugal force acting on spacecraft in circular orbit with ...
10
votes
2answers
920 views

Orbits around the Photon sphere of a black hole (Schwarzschild coordinates)

This is a follow-up question to the answer given at What is the exact gravitational force between two masses including relativistic effects?. Unfortunately the author hasn't been online for a few ...
1
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2answers
43 views

Reference frame, gravitation and kinetic energy

English is not my primary language. I apologize (and would like corrections) if the terms I use are not the right ones. In a geocentric reference frame, the moon rotates around the Earth. So its ...
0
votes
1answer
87 views

As planets orbit around the Sun, does the force of gravity due to the Sun remain constant?

I know that the force of gravity is: $$F = GMm/R^2$$ Where $G$ is gravitational constant, $M$ is mass of sun, $m$ is mass of the orbiting planet and $R$ is the distance between the center of their ...
0
votes
2answers
52 views

Would an astronaut floating in space at zero speed get drawn to the Earth?

The question came to mind after watching this video: http://www.youtube.com/watch?v=MTY1Kje0yLg If the Earth and Moon can bend space-time, and if the Earth's gravity is strong enough to reach the ...
0
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0answers
43 views

What would be the long-term effects of stopping the Sun?

TL;DR: In an orbital simulation, what are the effects of pinning the major body to the origin, and how could these effects, if any, be mitigated? Consider an orbital motion simulator; your basic n-...
3
votes
1answer
36 views

Orbital parameters of more than two bodies

I am not even entirely sure that the question makes sense except in certain simple cases, but let me explain what I am trying to do, but with the question first. The question is essentially: Given n ...
0
votes
1answer
42 views

Velocity Related To Gravitation [closed]

Which Equation is correct $v^2=\large{\frac{2GM}r}$ OR $v^2=\large{\frac{GM}r}$? I am getting confused here.
1
vote
1answer
48 views

Distance of closest approach of a satellite after star explodes [closed]

Problem: A satellite is in a circular orbit about a star, when it explodes spherically symmetrically, to a large distance from the star and in negligible time. The star loses 2% of its mass. I want ...
-7
votes
3answers
84 views

Why doesn't the earth collide with the sun in 64 years?

According to another answer on this site, the time it takes for two bodies in space to collide can be computed with the following formula: $$\frac{\pi}{2\sqrt{2}}\frac{r_0^{3/2}}{\sqrt{G(M+m)}}$$ ...
16
votes
8answers
4k views

Why doesn't orbital body keep going faster and faster? [duplicate]

If we consider the change in velocity during an infinitesimal interval of an orbit: where body B is orbiting body A, we can see that the magnitude of the resultant vector (the green arrow) is ...
3
votes
1answer
24 views

Orbital Velocity & LLR

As I understand it, light that is emitted from a source is not imparted with the motion of the source and so always follows a "straight line". If this is correct, I am having a difficult time ...
-5
votes
1answer
86 views

What is exact difference between gravitational force and magnetic force? [closed]

I've read that gravitational force is due to mass only and magnetic field is due to moving charged particles. But my question is: what are other difference between them? Can we set up a small ...
0
votes
0answers
30 views

Keplerian orbits and radial velocities: problem with true anomalies

I am writing a pure Python code to calculate radial velocities of stars with massive objects orbiting them. I am following the formalism from Murray & Correia (2011) (hereafter MC11). In a given ...
30
votes
3answers
7k views

If we threw a baseball from the ISS, could we deorbit the ball?

Clearly this is a hypothetical question. Say we bring a star baseball player into NASA, prep them appropriately for a mission in space, and fly them up to the International Space Station. They go on ...