Answer
a) $F=kw s^2/r$
b) $48~mi/hr$
Work Step by Step
a) According to the exercise, we have the equation:
$F=kw s^2/r$
for some constant $k$.
b) We plug in the given values to obtain:
$k(1600)(60)^2/r=k(2500)s^2/r\\s^2=2304\\s=\sqrt{2304}=48~mi/hr$