An engineer in a locomotive sees a car stuck on the track at a railroad crossing in front of the train. When the engineer first sees the car, the locomotive is 190 m from the crossing and its speed is 18 m/s. If the engineer’s reaction time is 0.54 s, what should be the magnitude of the mini- mum deceleration to avoid an accident? Answer in units of m/s2.
-
in 0.54 s the train travels 18 . 0.54 = 9.72 m
Remaining distance to car = 190 – 9.72 = 180.28 m
a = V^2 / 2 . d = 18^2 / 2 . 180.28 = 0.898 = 0.90 m/s/s
Remaining distance to car = 190 – 9.72 = 180.28 m
a = V^2 / 2 . d = 18^2 / 2 . 180.28 = 0.898 = 0.90 m/s/s