Please help me with a physics problem (acceleration)?

Question

A freight train has a mass of 1.7x10^7 kg. If the locomotive can exert a constant pull of 8.4x10^5 N, how long does it take to increase the speed of the train from rest to 84 km/h?

I've looked in my physics book and cant figure out what equations to combine to figure this out! help please

Answer 1

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F=ma

8.4*10^5=1.7*10^7*a

a = 0.0494 m/s^2

84km/hr / 3.6 = 23.33m/s.

a = (v_f-v_i)/t

0.0494=23.33/t

t = 23.33/0.0494

= 472 seconds.