PX285 - A2a - conservation laws

momentum

\vec{p} = m \vec{v}

\vec{p} = \sum_{i} m_{i} {\vec{v}}_{i} = \sum_{i} {\vec{p}}_{i}

\frac{d \vec{p}}{d t} = 0

the total angular momentum due to the rotation of a mass/masses about some axis is conserved
the angular momentum:

\vec{L} = \sum_{i} m_{i} ({\vec{r}}_{i} \times {\vec{v}}_{i})

\vec{v} = \vec{ω} \times \vec{r}