From Mechanics

\displaystyle \begin{align} & F\le \mu R \\ & R=mg=1500\times 9\textrm{.}8 \\ & F=m\frac{{{v}^{2}}}{r}=1500\times \frac{{{15}^{2}}}{80} \\ & 1500\times \frac{{{15}^{2}}}{80}\le \mu \times 1500\times 9\textrm{.}8 \\ & \\ & \mu \ge \frac{{{15}^{2}}}{80\times 9\textrm{.}8} \\ & \mu \ge 0\textrm{.}287 \\ \end{align}