Afreight train has a mass of 1.0 ✕ 107 kg. if the locomotive can exert a constant pull of 6.9 ✕ 105 n, how long does it take to increase the speed of the train from rest to 68 km/h?

or

Explanation:

The force pull of 6.9x10^5 N increase the speed of the train from the rest to 68 km/h

so:

Now knowing the acceleration and using the equation of uniform accelerated motion can find the time:

Solve to t:

or

96.77 amp

explanation:

rl = 250/100 = 2.5 ohms.

egl = 250 + (100 × 0.1) + 2 = 262 v.

at 700 r.p.m., eg2 = 262 × 700/1000 = 183.4 v.

if ia is the new current, then eg2 - 2 - (ia × 0.1) = 2.5 ia

which means this will give ia = 96.77 amp.