Answer:
The time to reach 31.6 m/s is 14.54 s.
Step-by-step explanation:
Given;
acceleration of the locomotive, a = 1.60 m/s²
distance traveled by the locomotive, s = 20 m
time of motion, t = 2.4 s
final velocity of the locomotive, v = 31.6 m/s
The speed of the of the locomotive as it leaves the 20 m wide crossing;

The time to reach 31.6 m/s is calculated from the equation below;
v = u + at
31.6 = 8.333 + 1.6t
1.6t = 31.6 - 8.333
1.6t = 23.267
t = 23.267 / 1.6
t = 14.54 s
Therefore, the time to reach 31.6 m/s is 14.54 s.