Unraveling the Confusion: Coriolis Effect on a Frictionless Air-Hockey Earth

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    Confusion Coriolis
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Discussion Overview

The discussion revolves around the Coriolis effect and its implications on the motion of a frictionless air hockey puck on a hypothetical air-hockey Earth. Participants explore how the puck's trajectory would compare to that of satellites and question the accuracy of representations in existing literature on the Coriolis effect.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • One participant questions whether a puck shoved North would trace a sinusoidal path like a satellite or a small circle as depicted in the Wikipedia article on the Coriolis effect.
  • Another participant argues that the Wikipedia article may only consider the Coriolis effect without accounting for centrifugal force, suggesting that the wind speed mentioned is much less than that of a low orbit satellite.
  • A different viewpoint suggests that centrifugal force is equivalent to the Coriolis force, positing that a frictionless bullet fired North would curve West due to the differing speeds of the ground beneath it.
  • Some participants clarify that the paths described in the rotating frame are distinct from those in a non-rotating reference frame, indicating a need for further contemplation on the topic.

Areas of Agreement / Disagreement

Participants express disagreement regarding the interpretation of the Coriolis effect and its implications for the puck's trajectory. There is no consensus on the accuracy of the representations in the Wikipedia article or the relationship between centrifugal force and the Coriolis effect.

Contextual Notes

Participants highlight the limitations of existing explanations, noting that the discussion relies on assumptions about frictionless motion and the effects of rotation on trajectories.

peanutaxis
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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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peanutaxis said:
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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A.T. said:
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."
 
peanutaxis said:
My understanding is that the centrifugal force IS the Coriolis force.
No

peanutaxis said:
"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.
 
A.T. said:
No

Yes, but the circles are paths in the rotating frame.

Ah, okay. Thanks. Looks like I have more thinking to do. :)
 
peanutaxis said:
Ah, okay. Thanks. Looks like I have more thinking to do. :)

This might help:

 

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