\left\Vert \overrightarrow{A_{1}}\right\Vert = Km \left\Vert \frac{\overrightarrow{\Delta}} {\Delta^{3}} + \frac{\overrightarrow{r}} {r^{3}} \right\Vert = \frac{Km}{\Delta^2} \sqrt{\Big{(} \frac{\overrightarrow{\Delta}} {\Delta} + \frac{u^2\overrightarrow{r}} {r} \Big{)}.\Big{(} \frac{\overrightarrow{\Delta}} {\Delta} + \frac{u^2\overrightarrow{r}} {r} \Big{)} }