I understand that according to one of Euler's theorems, any solid object's 3D rotational orientation can be represented by a single 3D vector and an amount, i.e. a 4D vector.

However, is it correct to extend this to momentum? i.e. is it correct that a solid object's rotational momentum can be expressed by a vector? Or are there more complicated factors at play (e.g. wobble, etc.)

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    $\begingroup$ This link might be helpful: physics.stackexchange.com/questions/28955/… One of the features that I found confusing regarding angular momentum is that its calculation is dependent on the arbitrary choice of axis. A mass moving in a straight line has an angular momentum relative to an arbitrary point off that line. $\endgroup$
    – DWin
    Commented May 16, 2016 at 1:06

1 Answer 1


Of course it can. Angular momentum (the rotational analog to linear momentum) can be expressed as an axial vector (sometimes called pseudovector), which means a quantity that is similar to a regular vector, except for the fact that it changes sign under improper rotations (such as reflections). I suppose you're refering by "wobble" to nutation, i. e., a small oscillation on the axis of rotation of a spinning object, such as a top.
This is related to the presence of an external torque, which produces an angular acceleration, then a change on angular momentum:


For a more detailed explanation of the mechanism behind the nutation effect, see the answers to this question.


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