Since we are given a deceleration with a unit of ft/s2, it is convenient to convert 50 mi/h to ft/s. Appropriate conversion factors can be seen in the internet or in books.
50 mi/h = 73.33 ft/s
the equation for the distance travelled is
x = Vo*t - 0.5*a*t^2
where
x = distance travelled
Vo = initial velocity
t = time of travel
a = deceleration
since the time of travel is not known, we can find this using the equation
V = Vo - at
where V is the final velocity equal to zero (comes to stop)
substiruting values we get t = 1.67 s
therefore
x = 61.1 ft (0.01 mi)
