Originally Posted By: paul
4000N is the total amount of force required to accelerate a 100kg mass
to an acceleration rate of .8 m/s/s
over a distance of 1000 meters
in 50 seconds


You understand that a constant force causes a constant acceleration, right?

As soon as you apply 80N to the 100kg mass, it will immediately be accelerating at 0.8m/s/s. It won't increase to 0.9m/s/s if you wait longer. Of course in real life you can't apply a force instantly, but you can do it pretty suddenly and get 0.8m/s/s almost immediately.