# 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?

closed with the note: too conceptual
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.