Orbit Definition and 1000 Threads

  1. nysnacc

    Earth orbit -- geosynchronous orbit calculation

    Homework Statement Homework Equations ε= r_max - r_min / r_max + r_min = r*v2 / gRE The Attempt at a Solution I first find that 1 revolution is 2π rad , the angular velocity ω = 2π rad / 24h = π/43200 rad /s so v = rω where r is the unknown ε = 0 (circular orbit) r*(rω)2 / g RE = 0Correct...
  2. AlenC

    B Simulating orbit trajectory based on position and velocity

    Hi! I hope I'm posting in the correct section. I found this very similar topic in this forum: https://www.physicsforums.com/threads/orbital-ellipse.482713/ Aside from very helpful formula for calculating semi-major axis, the question was left unanswered. I have a working simulation of...
  3. Noisy Rhysling

    Stability of Polar Solar Orbits: Can a Planet Change its Host Star?

    I need a planet to be orbiting it's sun in a polar orbit. Is this a stable configuration?
  4. I

    How can we calculate the intercept time for a NEO on a hyperbolic trajectory?

    Homework Statement Hi! I was wondering how one can calculate the time we have to intercept and destroy a NEO? I have the semimajor axis, eccentricity, true anomaly, (v) inclination and r (a negative value) for the object, but I don't know where to begin). Homework Equations All the orbital...
  5. Irfan Nafi

    B How do stars orbit the center of the Milky Way?

    I've been wondering how all the stars of the Milky Way orbit the center of the Milky Way almost like it orbits Sagittarius A*. It is possible that there is a common center of mass that happens to be in the center of the Milky Way that also happens to be in the center, ultimately giving it its...
  6. I

    Is the Analysis of the Space Shuttle's Orbit Correct?

    Homework Statement Hi, I have a textbook problem from a course that I need help with Question: You’ve just completed an analysis of where the Space Shuttle must be when it performs a critical maneuver. You know the shuttle is in a circular prograde orbit and has a position vector of...
  7. G

    What is the Orbit of Hydrogen Atom for an Electron at 734 km/s?

    Homework Statement On which orbit of hydrogen atom an electron has the speed of 734 km/s? Homework Equations Bohr's second postulate: mvr=nh,m=9.109\cdot 10^{-31}kg,v=734 km/s,h=6.626\cdot 10^{-34} m^{2}kg/s The Attempt at a Solution By using the second Bohr's postulate, we get 6686.006\cdot...
  8. S

    A Planar orbit of planets around sun

    Imagine thee planets interacting through gravity, mathematically how should they come and rotate in a same plane, like planets and sun?
  9. P

    A Metric for Circular Orbit of Two Bodies

    I finally found a result I believe for the the asymptotic metric (valid for large r) of a pair of bodies in a circular orbit emitting gravitational waves. I use spherical coordinates, ##[t, r, \theta, \phi]##. If we let the linearized metric ##g_{\mu\nu}## be equal to the sum of a flat metric...
  10. H

    Orbit: impulse making orbit spherical

    Homework Statement A satellite moving in a highly elliptical orbit is given a retarded force concentrated at its perigee. This is modeled as an impulse I. By considering changes in energy and angular momentum, find the changes in a (semi major axis) and l (semi latus rectum). Show that \delta...
  11. Sveral

    B Gravitational Orbit: How Size Determines Distance & Speed

    Hello, was just wondering, what determines the gravitational orbit of an object orbitting a planet, for example, Saturn. Would increasing the size of the object decrease the distance between the object and the planet? Also, what determines the speed at which anything moves throughout it`s...
  12. Oganesson

    I Is Jupiter too big to orbit the Sun?

    I read the Jupiter is so big that it doesn't really orbit the sun. Is that true?
  13. avito009

    I Focus of Earth's elliptical orbit

    If the orbit of the Earth has only one focus which is the Sun then why can't it move in a circular path. Since a circle has only one focus and that is at the centre. Why is the sun the only focus when the path of Earth is an ellipse?
  14. D

    Angular velocity of circular orbit, small oscillations

    Homework Statement The potential energy of a particle of mass m is V(r) = k/r + c/3r^3 where k<0 and c is a small constant. Find the angular velocity \omega in a circular orbit of radius a and the angular frequency \omega' of small radial oscillations about this circular orbit. Hence show...
  15. D

    New orbit of satellite deflected by Jupiter

    Homework Statement This question involves parts of other questions, so I will state the relevant parts and essentially what the question is asking. It is from Kibble Classical Mechanics, Chapter 4, Question 22. If more information is needed I will provide. We have a satellite that orbits the...
  16. Alltimegreat1

    I How to define the rotation of a planet in retograde orbit?

    If a planet is in retrograde orbit, what direction would it rotate to also have retrograde rotation?
  17. Just144Ice

    Find Density Given Period of Orbit

    Homework Statement A satellite is in a circular orbit very close to the surface of a spherical planet. The period of the orbit is 2.53 hours. What is the density of the planet? Assume that the planet has a uniform density. Homework Equations T^2=(4pi^2r^3)/GM V=4/3piR^3 Density= Mass/...
  18. K

    Orbital Perturbations: Solving for Equations of Motion in Elliptical Orbits

    Homework Statement Say I have some planet in a circular orbit around a star, and I give it a small radial push (directly toward or directly away from the star). How would I describe the new orbit? I.e. how would I determine the equations of motion? h Homework Equations Kepler orbital radius...
  19. I

    B Calculating distances with an elliptical orbit

    Wasn't sure exactly what the title of this post should be. Working on a side project using machine learning and the solar system (using n-body simulator). Let's say I have two bodies with coordinates: Body1: x=-1.42790218981 y=1.4003882805 z=0.0 Body2: x=0.983274588755 y=0.0477301860159 z=0.0...
  20. T

    Do all electrons orbit in the ground state, when the band ga

    Do all electrons orbit in the ground state, when the band gap, is increased, or decreased, as atoms come together to form molecules.? Like in glass, transparent liquids, and plastics. As atoms come together to form glass, like silicon, sodium, and calcium. Do the electrons orbital permanently...
  21. Jenab2

    The Time to Fall in a Plunge Orbit

    Homework Statement Two masses, M and m, are initially (at time t=0) at rest with respect to each other and separated by a distance d. They are affected only by their mutual gravitational attraction. Find the amount of time elapsed beginning at the instant the separation is equal to d/2 and...
  22. Umair Shariff

    Fictional physics problem -- Firing projectiles into Earth orbit

    Hi guys, I've recently been reading a lot of Jules Verne and I had a few curiosities that you guys could help with. First, if we were to shoot or fling a bullet to low Earth orbit, what would the muzzle velocity have to be?? Second, instead of a bullet, if we used a capsule with one passenger...
  23. Jenab2

    I Position and Velocity in Heliocentric Ecliptic Coordinates

    There have been many questions on this forum about celestial mechanics in general, and concerning position and velocity in an orbit in particular. So I offer this post as a summary and reference. Here's a method for finding heliocentric position and sun-relative velocity in ecliptic coordinates...
  24. T

    I Derivation of planetary orbit equation with Lagrangian

    I am stuck at this part page 1, $$\frac{\partial{L}}{\partial{\dot{φ}}}=\mu{r^2}\dot{φ}=const=l------->\dot{φ}=\frac{l}{\mu{r^2}}......(8)$$ Why is this a constant? Isn't r and dφ/dt variables of time? Source: http://www.pha.jhu.edu/~kknizhni/Mechanics/Derivation_of_Planetary_Orbit_Equation.pdf
  25. L

    B What do you call rocks that don't orbit the sun?

    I understand the difference between comets, asteroids, and meteoroids. I was just reading about asteroids recently, and it occurred to me that when I read anything about these three types of objects the implicit (and sometime explicit) assumption is that they only apply to things that orbit the...
  26. P

    What Is the Minimum Velocity Factor for a Lunar Orbit?

    Homework Statement Compute the escape velocity for a projectile fired from the surface of the moon. The moon’s radius is 1700 km, and its surface gravity is ##1.62 m s^(−2)## . Neglect the effect of the Earth. A second projectile is fired horizontally from the lunar surface with a velocity f...
  27. T

    What is the speed of Sputnik I when it was at its perigee around Earth in 1957?

    Homework Statement Sputnik I was launched into orbit around Earth in 1957. It had a perigee (the closest approach to Earth, measured from Earth's center) of 6.81 × 106 m and an apogee (the furthest point from Earth's center) of 7.53 × 106 m. What was its speed when it was at its perigee? The...
  28. R

    Satellite in circular orbit with friction

    Homework Statement A satellite with mass 848 kg is in a circular orbit with an orbital speed of 9640 m/s around the earth. What is the new orbital speed after friction from the earth’s upper atmosphere has done -7.50·109 J of work on the satellite? Does the speed increase or decrease? Homework...
  29. Zayl

    I Question about Mercury's orbit discrepancy

    http://physics.ucr.edu/~wudka/Physics7/Notes_www/node98.html In the link given below, it is explained how general relativity predicts the correct results. However I am curious about the answer of the following hypothetical scenario. Let us assume that we replaced gravity with the...
  30. E

    Tangential acceleration in elliptical orbit?

    Homework Statement A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the mass of the earth. Choose the correct statement. Ans: (A) the acceleration of S is always directed towards the centre of the earth Homework Equations F=...
  31. H

    I Why must the oscillatory period of a stable orbit be constant at all distances

    Consider a stable circular orbit (with a central force) subjected to small perturbations. The orbit equation is given by (3.45). The text argues that the ##\beta## in (3.46) must be a constant over the domain of ##r_0##: "Otherwise, since ##\beta## can take on only discrete rational values (for...
  32. FruitNinja

    Planet orbiting around a star whose mass changes

    Homework Statement (Assuming all circular orbits) [/B] Say there is a star with mass M and a planet orbiting that star with a mass m. The star M then suddenly loses half of its mass. (So now it is M/2) What is the new radius of orbit of the planet around the star? Warning: Velocity will not...
  33. H

    Orbit invariant under reflection about apsidal vectors

    The book argues that since substituting ##\theta## by ##-\theta## leaves the orbit equation (3.34) unchanged, the orbit is therefore invariant under reflection about the apsidal vectors (Fig 3.12). If substituting ##\theta## by ##-\theta## leaves the orbit equation (3.34) unchanged, then there...
  34. FruitNinja

    ORBIT: change in orbital distance

    Homework Statement we know the mass of the moon, Mm, and the Earth's, Me, and also the initial distance between their centers as the moon orbits the earth, Rem. Now if the earth’s angular velocity about its own axis is slowing down from a initial given angular velocity, ωi to a final angular...
  35. P

    Geostationary satellite orbit radius as a multiple of Earth radius.

    Homework Statement Okay, so the question seems really simple so I don't know what I'm missing A satellite orbits at a fixed point above the Earth's equator. Assuming the Earth has uniform density, radius R, and angular frequency of rotation, omega Find an expression for eta, such that the...
  36. U

    Gravitational Potential Energy in orbit

    This pertains to a homework question but I get the concept of PE or U = -GmM/a for an elliptical orbit. I also understand the derivation of the total energy of an object in an elliptical orbit as E = -GmM/2a. However, I have a homework question that asks for the ratio of an object's kinetic...
  37. S

    Planet traversing the half of its orbit closest to the sun?

    Homework Statement What fraction of its "year" (i.e. the period of its orbit) does a planet spend traversing the half of its orbit closest to the sun? Give the answer in terms of the eccentricity ε of the planet's orbit. This is problem 15 from page 852 of Adam's Calculus 3ed. No detailed...
  38. Giu1iano

    Solving Satellite Orbit Problem: Finding Time in Hours

    The problem is as follows. "NASA places communication satellites into Earth orbit with a radius of 42000 km. If the centripetal acceleration of one of the satellite is 0.22m/s^2, how long, in hours, will it take this satellite to make one complete orbit? For this chapter, these are the...
  39. josh0196

    B Can an object have too little mass to have a stable orbit?

    I was wondering, since gravitational atttraction is determinated by m1 * m2 / d2 * G , can an object have a mass too little to have a stable orbit, for instance, around the sun? P.S: I'm new to this forum! Hello!
  40. Geoff Pollock

    Acceleration in an Elliptical Orbit

    So let's say you are on an orbital satellite in an elliptical orbit around our planet Earth, meaning that the at one point in the orbit you are going faster, due to the gravitational pull of the planet. Would you feel the acceleration in space due to the shape of the orbit?
  41. R

    Conundrum of Solving True Anomaly in Binary Orbits: A Scientist's Dilemma

    I have a real doosy that has got me stumped. I need to solve the following equation for v: tan(v + ω) = tan(θ + Ω)sec(i) The symbols stand for the following values in an elliptical orbit of one point source around another (on the celestial sphere): where v = true anomaly; ω = argument of...
  42. Luke Cohen

    Find the min/max r of particle with a central force

    Homework Statement A force field in 2-d F~ = −kr(rˆ) with U(r) = k(r^2)/2 acts on a particle of mass m. The particle is now in a non-circular orbit. In terms of the particle’s angular momentum L and energy E, d) What is its closest approach to the origin? e) What is its furthest distance from...
  43. A

    What causes orbits to change over time?

    There are two examples: A planet rotating around a star and a spacecraft maneuvering through space. Let's assume that solar radiation has no affect on the spacecraft and the spacecraft is not bumping into any stuff, and niether is the planet; and no other gravitational sources are involved...
  44. T

    Proper movement, reference frames and gravitational waves

    Hi, So apparently electrons don't orbit the nucleus of atoms so I'm assuming the lack of movement means that no energy from the atom is radiated away from an atom due to minuscule gravitational waves, over the life of the universe. But gravitational waves have got me thinking about reference...
  45. A

    Why won't objects fall out of orbit

    I kind of understand how orbit works. So an object falls 10 feet then the Earth's curve counteracts the 10 feet, so it's prevents the object from just crashing down to earth. But wouldn't the object slowly either come closer to Earth or go away from earth. As in like millimeter by milimeter.
  46. Nineways

    Computing 'Sound' Frequency of a Planet: Possible Methods?

    Is there an accurate method in computing the 'sound' frquency of a planet? For example, taking the orbital path of say Jupiter for one year, and computing it into an audible frequency? I'm looking for ways to compute this, but I am at a loss to where the best starting point is. Could Bohr's or...
  47. L

    Does a Radially-Impulsed Astronaut on the ISS Return to the Same Spot?

    I understand that if there is a body in a circular orbit around the Earth (or any other thing), and there is an impulse directed radially out away from the Earth against the orbiting body, the body will end up in an elliptical orbit, which will pass through the original circular orbit. This got...
  48. henrco

    What is the radius of the orbit of an electron

    Hi All, Having difficultly figuring out where I've gone wrong with this problem. Any guidance gratefully received. 1. Homework Statement A 4.76 keV electron (an electron that has a kinetic energy equal to 4.76 keV) moves in a circular orbit that is perpendicular to a magnetic field of 0.392...
  49. Cobalt101

    Orbit precessions - General Relativity vs Newton

    What is the underlying feature of general relativity that, unlike Newtonian mechanics, results in the correct calculation of orbits i.e. including precession (e.g. Mercury). I not asking for the mathematics (i.e. the additional term in the equation) but rather what underlying "physical"...
  50. M

    How often do satellites pass the moon?

    So, I have really no background in astrophysics (other than touching on some areas in general physics and calculus). I understand that asking questions such as the one in my title, that I would need to be more specific, and I will attempt to be as specific as I can. I understand that most...
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