Question

a train comes to a stop in 3 minutes. if the train had a uniform acceleration of -3.5 m/s/s what was initial velocity of the the train?

Answer 1

3 minutes = 180 seconds.
If it spent the entire 180 seconds slowing down at the rate of 3.5 m/s every second, then it began the 3 minutes at the speed of (180 x 3.5)=630 m/s. That's about 1,409 mph !