# Conservation of Angular Momentum

1. ### pwn01

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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.

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3. ### Jilang

629
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.

4. ### pwn01

11
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?

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