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

• I
• peanutaxis
In summary, the space station's circles are caused by centrifugal force and the puck's circles are caused by Coriolis force.

#### peanutaxis

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.

Last edited:
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.

Last edited:
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:

## 1. What is the Coriolis Effect?

The Coriolis Effect is a phenomenon that causes objects in motion on a rotating surface, such as the Earth, to appear to curve in a different direction than they would if the surface were not rotating. It is caused by the rotation of the Earth and is responsible for the rotation of large-scale weather systems and ocean currents.

## 2. How does the Coriolis Effect affect objects on a frictionless air-hockey Earth?

On a frictionless air-hockey Earth, the Coriolis Effect would cause objects to follow a curved path instead of a straight line. This is because there is no friction to counteract the force of the Coriolis Effect, causing the objects to continue moving in a curved path.

## 3. What is the significance of the frictionless air-hockey Earth in understanding the Coriolis Effect?

The frictionless air-hockey Earth is a simplified model that allows scientists to isolate the effects of the Coriolis Force and understand its impact on motion. By removing friction, scientists can observe how the Coriolis Effect alone affects the movement of objects on a rotating surface.

## 4. How does the Coriolis Effect differ between the Northern and Southern Hemispheres?

In the Northern Hemisphere, the Coriolis Effect causes objects to appear to curve to the right, while in the Southern Hemisphere, objects appear to curve to the left. This is due to the direction of rotation of the Earth. The Coriolis Effect is also stronger near the poles and weaker near the equator.

## 5. Can the Coriolis Effect be observed in everyday life?

Yes, the Coriolis Effect can be observed in everyday life in various ways. For example, it is responsible for the direction of rotation of large-scale weather systems, the path of ocean currents, and the direction of swirling water in a bathtub or sink. It also affects the trajectory of thrown objects, such as a football or a frisbee.