Need Help with somthing

Discussion in 'Astronomy, Exobiology, & Cosmology' started by zombieman, Jun 30, 2011.

  1. zombieman Registered Member

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    Ok say we have a planet getting rings around it. what if after time the rings around the planet exceeds the gravity of the planet. what happens to the planet
     
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  3. Cifo Day destroys the night, Registered Senior Member

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    Please explain what you mean by exceeding the gravity.
     
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  5. cosmictraveler Be kind to yourself always. Valued Senior Member

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    I don't think that anything would happen to the planet because as anything increases its size, as the rings you are talking about, those would become so heavy that they would be attracted by the planets mass and be pulled down into the planet. So the things that make up the rings could only grow to a certain size and as they do their orbits will decay and start to fall into the planet.
     
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  7. Kel "Not all who wander are lost." Registered Senior Member

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    If by exceeding the gravity you mean an increase in velocity then they will slingshot out of orbit. Otherwise they will, as traveler said, fall into the planets gravity well and either burn up in the atmosphere or impact with the surface of the planet itself. However if it is a gas giant they will most likely burn up and depending on the gasses make some some pretty explosions.
     
    Last edited: Jul 2, 2011
  8. orcot Valued Senior Member

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    a small body and a large body are equally attracted by gravity, so mass will not make it fall into the planet any faster. But if matter in the ring would somehow increase in mass then the density would increase and a high density zone where particles travel relativly at the same speed, will cause it to clumb together and basicly make a solid moon. If that new moons mass kept increasing and we ignore that it's mass should come from somewhere else and thus has it's own velocity then the main body would increasingly wobble until it's barry center is outside it's own surface making the body's orbit around each other and thus making it a double planet.
     
  9. cosmictraveler Be kind to yourself always. Valued Senior Member

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    How is it that when something increases its mass it goes even faster?:shrug:
     
  10. jbor Registered Member

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    Not sure that's what was meant: However, when something goes faster, it does increase it's inertial mass (of momentum using relativity theory).
     
  11. cosmictraveler Be kind to yourself always. Valued Senior Member

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    I was asking orcot about his idea so if you read his thoughts it would seem he is saying that as the debris in the ring combine they gain mass, which to me would suggest they would be pulled down to the even heavier mass of the planet if they became heavy enough, and form a small moon which would have to increase its speed somehow to keep in the orbit because its mass is many times heavier now that it has become a small moon. That small moon , if it stays at the same speed, would be pulled down to the planet faster because of its new weight and therefore lose speed as well not increase speed to make up the difference of its weight to counter the pull of the planet. I hope that explains what I meant.
     
  12. OnlyMe Valued Senior Member

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    The rate at which two objects of differing mass fall toward a source of gravitation, is not dependent upon their mass. See Galileo. Absent air resistance objects of different masses fall to earth at the same rate, or "speed".

    An object in orbit is essential falling around the earth or other source of gravitational influence. Two objects of differing masses fall around (orbit) a gravitational center at the same velocity without consideration of their mass, given that there is no air resistance or other outside force involved.

    IOW two objects of different masses, will remain in orbit at the same distance from the "planet" at the same orbital velocity. As you increase the mass of one it does not need to speed up to remain in orbit. It would require more energy to accelerate a larger mass to orbital velocity but orbital velocity remains the same for any given distance from the gravitational center.
     
  13. cosmictraveler Be kind to yourself always. Valued Senior Member

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    So if a object was 100 tons and became 500 tons within a few thousand years and it was in orbit around a large planet it wouldn't be slowed down when it gained that much more weight due to the gravitational pull on that now heavier object?
     
  14. OnlyMe Valued Senior Member

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    I will try to explain without a bunch of mathematics...

    Yes, an object with more mass would weigh more on the surface of the Earth and the Earth's gravitational pull would be greater on it,than on a smaller mass, even in orbit. What happens is that, it also has an equally increased inertia (resistance to a change in motion), so it would resist the greater gravitational pull and fall at the same rate as the smaller object.

    The only effect it should have on the orbit might be that the gravitational center of mass (barycenter) might shift. But if you are talking about a planet and an orbiting mass in the range of hundreds of tons it shouldn't be significant.

    Thinking of mass in terms of weight is misleading, though an object with more mass would would weigh more measured on the surface of the earth, it would still seem weightless in orbit.

    It would take more energy to get an object with more mass into orbit but once there, as long as that orbit is outside of the atmosphere, where there is not air resistance to its motion, the orbit would be at the same velocity regardless of the mass.

    I hope I did not mess that up too much.
     

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