Update textbook.fr.md

12.temporary_ins/40.classical-mechanics/30.n3/07.coherence/textbook.fr.md

@@ -575,11 +575,22 @@ $`\overrightarrow{OM}=\mathscr{l}\;\overrightarrow{e_{\rho}}`$
 
 $`\begin{align}
 \overrightarrow{\mathscr{v}_M}&=\dfrac{d\overrightarrow{OM}}{dt}\\
+\\
 &=\dfrac{d}{dt}\big(\mathscr{l}\;\overrightarrow{e_{\rho}}\big)\\
+\\
 &=\underbrace{\dfrac{d\mathscr{l}}{dt}}_{=\,0}\;\overrightarrow{e_{\rho}}\;+\;\mathscr{l}\;\dfrac{d\overrightarrow{e_{\rho}}}{dt}\\
-&=\mathscr{l}\;\omega\;\overrightarrow{e_{\theta}}\\
-&=\mathscr{l}\;\overrightarrow{e_{\rho}}\end{align}`$
+\\
+&=\mathscr{l}\;\omega\;\overrightarrow{e_{\theta}}
+\end{align}`$
+
 
+$`\begin{align}
+\overrightarrow{a_M}&=\dfrac{d\overrightarrow{\mathscr{v}_M}}{dt}\\
+\\
+&=\dfrac{d}{dt}\big(\mathscr{l}\;\omega\;\overrightarrow{e_{\theta}}\big)\\
+\\
+&=\underbrace{\dfrac{d\mathscr{l}}{dt}}_{=\,0}\;\omega\;\overrightarrow{e_{\theta}}\;+\;\mathscr{l}\;\dfrac{d\omega}{dt}\;+\;\mathscr{l}\;\omega\;\dfrac{d\overrightarrow{e_{\rho}}}{dt}
+\end{align}`$