A car driver moving at initial speed vi $=50[$mi$/$h$]$ on a horizontal surface saw a pedestrian and did his best to stop the car. The car traveled the distance L $=36[$m$]$ before a complete stop.

$($a$)(5$ points$)$ One mile is $1\mathrm{.}6$ km$.$ What was initial speed of the car in m$/$s$?$

$($b$)(15$ points$)$ Find the coefficient of friction between tires and the pavement. Assume that the force of friction was constant all the time.

$($c$)(5$ points$)$ How long would be the stopping distance if it was a wet road, when the friction coefficient is $2$ times smaller?