Answer
$f=275 N$
Work Step by Step
In the given scenario, the centripetal force is producing the force of friction so $F_c=f$ where $F_c$ represents centripetal force and $f$ stands for force of friction.
Since $F_c$=$\frac{mv^2}{r}$, $f=\frac{mv^2}{r}$.
Putting the values of $m$, $v$ and $r$ into the above formula, we get
$f=\frac{(85)(9)^2}{25}$
$f=275 N$
