A heavy freight train has a mass of 14000 metric tons. If the locomotive can pull with a force of 645000 N, how long does it take to increase it's speed from 0 to 69.8 km/h?

Answer 1

m = 14000 MT * 1000 kg/MT = 1.4*10^7 kg
MT = Metric Tons. m = mass.

F = ma,
a = F/m = 6.45*10^5 / 1.4*10^7 = 0.0457m/s^2.

V = 69.8 km/h * 1000 m/km * 1/3600 h/s =19.39 m/s.

a = (Vf - Vo) / t = 0.0457,
(19.39 - 0) / t = 0.0457,
19.39 / t = 0.0457,
Cross multiply:
0.0457t = 19.39,

t = 19.39 / 0.0457 = 424.3 s = 7.1 min.