# Questions tagged [orbital-motion]

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

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### Two different ways of finding the speed of a low-earth circular orbit [closed]

I would guess that in a secondary-school physics course, if you're asked to find the speed of a low-earth circular orbit, you might be expected to use the $v^2/r$ formula. But here's another way: Via ...
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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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### Restricted 3-body: one large mass and two smaller ones

A restricted 3-body problem is usually understood as two large bodies and one much smaller one that doesn't affect the motion of the other two. I am curious about a 3-body problem with one large body, ...
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### Dynamics problem [closed]

A 150-kg space vehicle passes through the origin of a newtonian reference frame Oxyz at time t = 0s with velocity o = (100 m/s)i relative to the frame. Following the detonation of explosive charges, ...
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### What changes the velocity perpendicular to radius in an elliptical orbit?

I'm working currently on a problem that asks to justify that angular momentum and kinetic energy conserves for a planet in an elliptical orbit. Although I've been taught that angular momentum should ...
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### Find eccentricity of orbit given the velocity and the semi-major axis

Is it possible to calculate eccentricity of orbit knowing only the semi-major axis and the velocity of both celestial bodies? If not, what other additional information is required. Does the fact that ...
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### The magnetic force between the earth and the sun

There is a magnetic field around the earth and a stronger one around the sun. I guess there should be a magnetic force between the sun and earth. Now, shouldn't we take the magnetic force into account ...
1 vote
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### Gravitational attraction between two bodies

While the gravitational force between two bodies is directly proportional to their masses, and inversely proportional to the distance between them is understandable / seems logical, how did Newton ...
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### Questions about speed of gravity [duplicate]

If gravity "travels" at $c$, and the sun is travelling "forward", does it mean the planets are actually orbiting various points "behind" the center of the sun? Does it ...
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### When are two object guaranteed to keep getting further and further away?

In a two-body problem, it is known (if I understand correctly) that if the specific orbital energy of the system is $\varepsilon \geq0$, then the objects must eventually escape each other. My question ...
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### Deflecting a lunar mass with consecutive nuclear explosions [closed]

I'm looking for help in determining the amount of deflection an object with a mass of roughly $7\times10^{22} \,\text{kg}$ (a lunar mass) needs from colliding with a planet. Let's stipulate that the ...
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### Would an Hypothetical Ringworld Positioned Inside the Moon's Orbit Around Earth, gravitationally affect Earth?

If a ringworld were to encircle Earth within the orbit of the Moon, would it induce any gravitational alterations on Earth? I grasp that inside a circular structure, there might not emerge a ...
1 vote
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### Which of Kepler's laws would remain true if the force of gravity were proportional to the product of squares of each masses?

I was asked this question recently on which of the Kepler's Three law would remain if we changed the force of gravitation to be proportional to the product of squares of each masses instead of just ...
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### Initial positions and velocities for the three-body problem

I have made a simulation of the three-body problem, it follows the euler's method of solving differential equations. I have tried some initial positions and velocities of the bodies and have observed ...
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### Despite tides the Moon, as far as I know, doesn't slow down. Where does the energy come from? [duplicate]

Hy, I don't have anything to do with physics, so please forgive me if I explain my question in a weird way ;) As the Moon rotates around the earth it is creating tides and waves on the earth. IE it's ...
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### Speed of satellite in elliptical orbit [closed]

A satellite $S$ orbits a planet of mass $M$ in an elliptical orbit. At perihelion, $S$ has a tangential velocity of $v_1$ and is distance $r_1$ from the planet. At aphelion, $S$ has a velocity of $v_2$...
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### With what vel. would you have to launch an object vertically up from the earth's surface for it to land back again at it's initial launching point?

[Can skip reading this part] First of all, Newtonian gravity shall be considered whilst trying to solve this question. It's been on my mind for a long, long time and has been bothering me since. I ...
1 vote
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### How do two things attracted to each other move in mechanics?

Okay very simply: If you have two objects in 1D and they're both attracted to each other by some force (say there's a spring pulling them both towards each other, or Coulomb's Law or something)... How ...
1 vote
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### Setting $u$ = escape velocity when calculating the maximum height of a thrown object

So, if I throw an object at some velocity $v$ at an angle θ, the maximum height reached by the object is $\frac{v^2\sin^2{\theta}}{2g}$ but, I know this isnt true. clearly in a weird way, the height ...
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### Constant speed (at terminal velocity) and zero $g$

I have read the question What would a person experience in a free-falling elevator in a shaft long enough to reach terminal velocity? here and the answer was that you feel exactly the same if the ...
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### Space-for-time Derivative Substitution in Solving for Elliptical Orbit

I am currently working on a simulation of the Newton's Cannonball thought experiment, in which a stone is launched horizontally from atop a tall mountain at a high speed (in the absence of air) and ...
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### Elevation angle of LEO satellite as a function of time

Let a point on Earth be denoted with (lon,lat,altitude). Let a LEO satellite be defined by its altitude and inclination. I would like to compute the angular speed and elevation as a function of time. ...
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### Orbit description in Schwarzschild metric

Suppose to have a restricted 2-body system (BH + star with $M_{BH}\gg M_{\mathrm{star}}$) and you want to describe the orbit of the star relative to the BH, i.e. in the Schwarzschild metric. Usually, ...
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### How close does a dwarf star have to be to remove the corona from its neighbour in an elliptic binary system?

It is possible for a larger (wider, but less massive) star to mutually orbit a heavy dwarf companion star in a binary system. If the dwarf star gets close enough it can attract the corona of the ...
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### How does moving the pericenter affect the apocenter?

A perfectly circular orbit of a constant height (distance from the center of mass of the orbited planet) around a perfectly spherical planet with smooth surface and no gravitational anomalies will ...
1 vote
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### Finding the Cartesian position of the lunar ascending node

What I'm trying to derive The Cartesian position of the lunar ascending node relative to the true equator and equinox of date reference frame. My issue is I'm getting a bit tripped up with reference ...
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1 vote
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### How stable are orbits of light objects around twin large bodies?

I know the two-body problem has a stable solution and the three-body problem does not. In the case that there are two comparable large bodies (twin planets) in a stable mutual orbit, what happens to a ...
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### Is it possible, by monitoring the brightness of stars, to find a “copy of the Earth + Moon” near them?

More than a dozen Earth-like planets have been discovered around nearby stars based on observations of changes in the brightness of their sun as they pass across its disk (transit events). If an Earth-...
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1 vote
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### Is there a way to use the distances of the two opposite apsides to determine the eccentricity of an orbit?

Is there a way to use the distances of the two opposite apsides to determine the eccentricity of an orbit? The ratio between the distances (i.e. perihelion & aphelion) seem like they'd have a ...
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### Time taken for an object to fall [duplicate]

Time taken for an object to fall is generally given by $$t=\sqrt{\frac{2h}{g}}.$$ But this is only true under the assumption that gravitational acceleration is constant. With variable gravity what ...
1 vote
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### Escape Velocity from Moon to escape Earth-Moon System

So the escape velocity at Earth is roughly 11.2 km/s, but with the escape velocity of the moon it says that it is 2.38 km/s but since the moon is orbiting the Earth, wouldn't the effective escape ...
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### Don't Geodesics change due to other geodesics?

So the geodesics that point towards the Earth brings space-time towards the Earth and then back out again, but then the moon has its own geodesics so wouldn't it be kind of like geodesics affecting ...
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### Anomalistic periods of Earth and Mercury

Can any one give me a TRUE VALUE for the anomalistic periods of Earth and Mercury? I note the previous question on the following. I more or less implemented the method suggested above using elliptic ...
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