What is the actual definition of rotational motion?

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SUMMARY

The discussion clarifies the definition of rotational motion, emphasizing that it encompasses more than just rotation around a fixed axis. The general case of rotational motion involves scenarios where the axis of rotation may be translating or rotating relative to another reference point. Key concepts include angular momentum, which remains constant in the absence of external torques, and the distinction between angular momentum and angular velocity when the rotation does not occur about a principal axis. This nuanced understanding is supported by Goldstein's text, "Classical Mechanics."

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  • Familiarity with fixed and translating axes of rotation
  • Basic knowledge of classical mechanics principles
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  • Study the concept of angular momentum in detail
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Ok so I roughly know what rotational motion is (e.g. the spinning of a DVD) but I wish to know the textbook definition for it. I tried Googling it but to no avail. The first link on Google gives this:

Rotation around a fixed axis is a special case of rotational motion

http://en.wikipedia.org/wiki/Rotation_around_a_fixed_axis

But as mentioned above, that is a special case only, so what is a general case of rotational motion? IE is there a definition for it?

Thanks
 
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The general case is where the axis of rotation itself may be translating or rotating w.r.t. another reference.
 
A free object does not in general rotate about a fixed axis. The object's angular momentum will be constant if no external torques are exerted on the object, but even that does not mean that it will rotate about a fixed axis. Angular momentum and angular velocity will point in different directions if the instantaneous rotation is not about one of the object's principal axes. The object will tumble. Or, as Goldstein puts it in his text Classical Mechanics, "The polhode rolls without slipping on the herpolhode lying in the invariant plane."
 

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