\(V_{\text {escape }}=\sqrt{\frac{G M}{R}}\)
\(\frac{V_{\text {escape Earth }}}{V_{\text {escape moon }}}=\sqrt{\frac{M_\theta}{R_\theta} \times \frac{R_m}{M_m}}=\sqrt{\frac{81}{4}}=\left(\frac{9}{2}\right)\)
\(\Rightarrow V_{\text {moon }}=\frac{2}{9} \times 11.2=2.48 \,km / s\)