fix typo, add missing image

uni/mmme/2xxx/2047_thermodynamics_and_fluid_dynamics/dimensional_analysis.md

@@ -62,7 +62,7 @@ This would take ages.
 This is where dimensional analysis helps as it means we only need 2 nondimensional groups
 to relate the 4 parameters: momentum coefficient, $C_m$, and Reynolds number, $Re$.
 
-$$C_m = \frac{T}{\frac12 \rho \omega^2D^5} \rightarow C_m = g(\text{Re})$$
+$$C_m = \frac{T}{\frac12 \rho \omega^2D^5} \rightarrow C_m = g(\text{Re})$$
 
 This suggests that the parameters can be reduced to a single parameters - the rotating
 Reynolds number.