# Regid Body¶

Center of mass $$\vec R$$ is defined as

$\int \rho(\vec r) \vec r d^3 \vec r = \int \rho(\vec r) \vec R d^3 \vec r .$

Equivalently,

$\int \rho(\vec r) \left( \vec r - \vec R \right) d^3 \vec r = 0.$

© 2017, Lei Ma. | Created with Sphinx and . | | | |