Thanks, for part A I used;
final velocity= initial velocity+ rate if acceleration x time = 14m/s
Distance during acceleration and deceleration = (14/2) x 20s = 140m
Distance= uniform velocity x time taken = 14x300s= 4200m
so answer to part a come to 140+4200+140=4480m
then part b 40tonnes =40,000kg
F=mxa = 40,0000x0.7 =28,000n =28Kn