Part A

A roadway is designed for traffic moving at a speed of $42\frac{m}{s}.$ A curved section of the roadway is a circular arc of $180$ m radius. The curved section is temporarily replaced with an unbanked roadway of the same radius. The coefficient of friction of this roadway is $0\mathrm{.}40.$ The maximum safe driving speed for this unbanked, curved section is closest to:

$21\frac{m}{s}$

$19\frac{m}{s}$

$25\frac{m}{s}$

$27$ m$/$s

$23\frac{m}{s}$