More Coriolis confusion

  • #1
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1
If earth was turned into an air-hockey planet, with no friction (or air friction), and I was in New York and I shoved an air hockey puck North, would the hockey puck trace out the same sinusoidal-type path that a satellite/space station does (spending an equal amount of time in the northern and southern hemispheres), or would it trace out one of the little circles in the picture on the right of this section of this article on the Coriolis Effect?

Something doesn't add up. If the puck would just do a small circle, then why don't space stations do small circles? For they are only 400km up? And if it would do space-station sinusoidal circles, then what the hell is with the Wiki article on Coriolis?!?

Thanks.

EDIT: "The coriolis force has no effect on the motion of an object when viewed from a non-rotating reference frame."
There is no way those small circles in the Wikipedia article are correct, because if they are, then what the hell is keeping my frictionless puck above the equator? There are no forces except gravity acting on my puck, so it is tracing a great circle which must dip below the equator.
 
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Answers and Replies

  • #2
A.T.
Science Advisor
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There is no way those small circles in the Wikipedia article are correct
I think it considers only Coriolis, not centrifugal force. Also wind speed of 70 m/s, much less than a low orbit satellite.
 
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  • #3
14
1
I think it considers only Coriolis, not centrifugal force. Also wind speed of 70 m/s, much less than a low orbit satellite.
My understanding is that the centrifugal force IS the Coriolis force. If you fire a frictionless bullet North from NY then it will curve to the West because the ground beneath it is moving slower than the latitude from which it was fired, and that this is the same as saying it will move in a Great Circle, and that this is the same as saying "The Coriolis force has no effect on the motion of an object when viewed from a non-rotating reference frame."
 
  • #4
A.T.
Science Advisor
11,006
2,481
My understanding is that the centrifugal force IS the Coriolis force.
No

"The Coriolis force has no effect on the motion of an object when viewed from a non-rotating reference frame."
Yes, but the circles are paths in the rotating frame.
 
  • #5
14
1
No

Yes, but the circles are paths in the rotating frame.
Ah, okay. Thanks. Looks like I have more thinking to do. :)
 
  • #6
A.T.
Science Advisor
11,006
2,481
Ah, okay. Thanks. Looks like I have more thinking to do. :)
This might help:

 

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