A freight train has a mass of 1.8 × 10

7
kg.
If the locomotive can exert a constant pull
of 6.2×10
5
N, how long does it take to increase
the speed of the train from rest to 70 km/h?
Answer in units of min.

1 answer

F = m a
6.2 * 10^5 = 1.8 * 10^7 a

a = (6.2/1.8)10^-2 m/s^2

v = a t

now what is v
70,000 m/3600 s = 19.4 m/s
so
t = (19.4 * 1.8 /6.2 )* 10^2 seconds