b
\(\mathrm{m}=800 \mathrm{~kg}\)

\(\mathrm{r}=300 \mathrm{~m}\)

\(\theta=30^{\circ}\)

\(\mu_2=0.2\)

\(\mathrm{~V}_{\max }=\sqrt{\operatorname{Rg}\left[\frac{\tan \theta+\mu}{1-\mu \tan \theta}\right]}\)

\(=\sqrt{300 \times \mathrm{g} \times\left[\frac{\tan 30^{\circ}+0.2}{1-0.2 \times \tan 30^{\circ}}\right]}\)

\(=\sqrt{300 \times 10 \times\left[\frac{0.57+0.2}{1-0.2 \times 0.57}\right]}\)

\(\mathrm{V}_{\max }=51.4 \mathrm{~m} / \mathrm{s}\)