First unify the units.
55.4 mi/hr = 24.8 m/s
you know that the distance is given by
s = 24.8t - 1/2 at^2
So, to stop in exactly 116 meters, we need
24.8t - 1/2 at^2 = 116
Now, we know that during that time, the speed reduces from 24.8 m/s to zero, so
a = 24.8/t m/s^2
t = 24.8/a
Thus we need
24.8(24.8/a) - 1/2 a (24.8/a)^2 = 116
a = 2.65 m/s^2
check:
t = 24.8/2.65 = 9.36 s
24.8(9.36) - 1/2 (2.65)(9.36^2) = 116.04
close enough for jazz
A driver in a car traveling at a speed of 55.4 mi/h sees a deer 116 m away on the road. Calculate the minimum constant acceleration that is necessary for the car to stop without hitting the deer (assuming that the deer does not move in the meantime).
I simply do not know how to set this up. Initial velocity is given, as well as distance. But how am I supposed to find anything else? I tried using final velocity as 0 and that didn't work.
1 answer