As illustrated below, a tornado can be approximated by a free vortex of strength $$ for $r>R_c$ where $R_c$ is the radius of the core. Velocity measurements at points A and B indicate that $V_A=40\frac{m}{s}$ and $V_B=20\frac{m}{s}.$ Determine the distance from point A to the center of the tornado. Why can the free vortex model not be used to approximate the tornado throughout the flow field? $($Hint: consider the velocity at the center of a free vortex and the actual velocity at the center of a tornado$)$