Center of Mass

Center of mass or barycenter (2 bodies): $r_c$ is distance of center from $m_1$ along line between bodies $r$ is distance between bodies $m$ is masses $r_c=r\frac{m_2}{m_1+m_2}$

Center of mass or barycenter (n>2 bodies): (Sum of product of all masses and their associated positions) $\overrightarrow{r_c}=\frac{\Sigma \vec{p}m}{\Sigma m}$

Mechanical Equilibrium

$\Sigma F$ Must equal zero to maintain linear state $\Sigma \tau$ about any point must equal zero to maintain rotational state If you put the point you are calculating at one of the forces, there’s less algebra