User talk:Egm6936.s09/EGM 6611 Continuum Mechanics, Fall 2003

\[\begin{array}{l} m(W,t) = \int\limits_W {\rho ({\bf{x}},t)dV({\bf{x}})} \,\, \\ \frac{d}m(W,t) = \frac{d}\int\limits_W {\rho ({\bf{x}},t)dV({\bf{x}})} = \int\limits_W {\frac({\bf{x}},t)dV({\bf{x}})}  \\ \int\limits_{\partial W} {\rho {\bf{u}}.{\bf{n}}dA} = \int\limits_{\partial W} {\rho {\bf{u}}.d{\bf{A}}}  \\ \end{array}\]