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Hello I am still confused about rotating coordinate frames and want to ask a question about it. Is it correct that strictly speaking the mass must be connected with the axis of rotation in the rotating coordinate frame? For example by a rod, or a rotary disk, or whatever. I mean otherwise I do not see how an Euler force or a Coriolis force can act on a particle? (I think I am confused because this connection is usually not showed in figures in the textbooks)

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  • $\begingroup$ Pseudoforces in non-inertial frames are not real forces and do not require any connection. $\endgroup$ – G. Smith Jul 3 at 19:43
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Is it correct that strictly speaking the mass must be connected with the axis of rotation in the rotating coordinate frame? For example by a rod, or a rotary disk, or whatever. I mean otherwise I do not see how an Euler force or a Coriolis force can act on a particle?

There is no need for a physical connection. These fictitious forces are artifacts of the coordinate system and any object described by that coordinate system is affected regardless of whether it is mechanically connected or not.

Consider, for example, a disconnected isolated object at rest in the inertial frame. In the rotating frame it “orbits” the axis in the anti-spin direction. There is no physical connection, so the only possible forces are the fictitious centrifugal and Coriolis forces. These sum to produce the observed motion, completely in the absence of a physical connection.

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    $\begingroup$ Indeed, assuming the rotation uniform, the sum of centrifugal and Coriolis forces is centripetal as is due for a uniformly rotating body... $\endgroup$ – Valter Moretti Jul 3 at 20:24

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