A train is moving with a velocity of 20 m/s . when the brakes are applied , the acceleration is reduce to -0.5m/s2 . calculate the distance covered by the train before coming to rest.

Answer 1

every second v decreases by 1/2 m/s
so, it takes 40 seconds to stop
The distance covered during time t is

s = 20t - 1/4 t^2

Now just plug in t=40