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Required velocity for a stable orbit?

  1. Jan 15, 2007 #1
    Say we have two objects. One is at the origin with mass = 1kg, the other is X meters away with mass 0.1kg

    Is there a way to calculate the velocity required to form a stable orbit, depending on the distance of the smaller object?
  2. jcsd
  3. Jan 15, 2007 #2
    Are you trying to calculate the orbital velocity, mr. qwesda?
  4. Jan 15, 2007 #3
    ^hey complex. i didn't know there was the term 'orbital velocity'

    googling this term should give me everything i need, thanks
  5. Jan 16, 2007 #4
    Hey guys ;) Depends on the size of the objects. If the objects are both points, then any sideways velocity will be enough for them never to collide because the conservation of angular momentum prevents it.

    The bigger the objects, the more tangential velocity they need, because they can't have their centres get closer than the sum of their radii, that would be a collision.
  6. Jan 16, 2007 #5


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    Is this not the case of equating circular motion forces with gravitational attraction forces...
  7. Jan 16, 2007 #6
    someone on another forum (BL) gave me this handy equation:

    crit_velocity = sqrt( 2*G*m1 / dist )

    where m1 is the mass of hte heavier object. note, this only works if hte mass of the lighter object is much much lighter than the heavier object

    if the velocity of the lighter object is less than the critical velocity, then it will form an orbit. if it's greater than the crit_vel, then it will fly off forever
    Last edited: Jan 16, 2007
  8. Jan 16, 2007 #7
    dont know why this was moved here, it wasnt hw, i'm not even in physics
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