# Conservation of momentum $\vec{L}$ and $\tau$ equations. [closed]

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• Is it possible to conserve angular and linear momentum to a rigid body from any frame or just from the ground frame of reference?

• My book says for reference point $A$, $$\frac{d L_A}{dt}=\frac{d}{dt}(I_{cm}\omega+\vec{r_{cm}} \times M\vec{v}) \neq I_A \frac{d\omega}{dt}$$ so torque equation can be applied to a rigid body in a general motion only and only about an axis through CM (center of mass). What does this mean?

Please give some examples and proof in support of your answer.

closed with the note: too conceptual
asked Jul 12, 2018
reshown Sep 21, 2018
Sorry but I think your question is not appropriate here, because it is **too conceptual** and too broad. This site is exclusively for **problem-solving exercises** in which you provide a specific exercise which you are trying to solve. See [Can I ask a question relating to a concept in the hope of understanding better?](http://physics.qandaexchange.com/?qa=1646/) and [Close reasons](http://physics.qandaexchange.com/?qa=128/).

Your question *might* be suitable for Physics Stack Exchange.