Conservation of Angular Momentum diagram

[pwn01]

Does the first diagram in the Wikipedia page: https://en.wikipedia.org/wiki/Coriolis_effect (that of the ball rolling on a rotating disk) properly illustrate the Coriolis effect or does it simply illustrate the conservation of angular momentum. I understand that these are two different principles.

 

[Jilang]

No, it demonstrates the conservation of linear momentum. The Coriolis effect is what is observed from a rotating reference frame. So if something is moving in a straight line in an inertial frame of reference it will appear to move in a circle in a rotating frame.

 

[pwn01]

Here is a quote from the caption "the observer. . . .sees the object as following a curved path due to the Coriolis and centrifugal forces present in this frame." So I gather from what your saying that the diagram does not actually illustrate the effect of the Coriolis "force" as indicated but rather the conservation of linear momentum. In other words, the observer is necessarily moved away from the ball because he has a higher linear velocity than the ball. The ball has a lower linear velocity because it started closer to the axis of rotation and does not acquire the velocity of the greater radius as it travels because this example is frictionless. The ball then actually falls behind and so appears to the observer to curve in its path. If I understand correctly, the Coriolis effect describes the phenomenon of the twisting of the reference frame below the object at any given point and the consequent change in its direction relative to the frame of reference. This has nothing to do with velocity (speed) and can be observed with a spinning mass gyroscope positioned correctly although it has no linear velocity, but does have inertia due to the spinning mass. Correct?

 

[pwn01]

I just came across this paper. I think that it clears everything up.

http://www.aos.princeton.edu/WWWPUBLIC/gkv/history/Persson98.pdf

 

[LudusRex]

The first diagram on the Wikipedia page does indeed properly illustrate both the Coriolis effect and the conservation of angular momentum. The Coriolis effect is seen in the curved path of the ball as it rolls on the rotating disk, which is a result of the conservation of angular momentum. This principle states that the total angular momentum of a system remains constant, unless acted upon by an external torque. In this case, the rotating disk provides the external torque that causes the ball to deviate from its straight path and follow a curved one. Therefore, the diagram effectively showcases both principles at play.