The train moved at a speed of 54 km / h and stopped 0.5 minutes after the start of braking

The train moved at a speed of 54 km / h and stopped 0.5 minutes after the start of braking. Determine the acceleration and the distance that it traveled from the moment of braking to a complete stop.

Data: V0 (train speed before braking) = 54 km / h (in SI system V0 = 15 m / s); t (time spent on braking) = 0.5 min (in SI system t = 0 s); V (final speed) = 0 m / s.

1) Determine the acceleration during braking: a = (V – V0) / t = (0 – 15) / 30 = -0.5 m / s2.

2) We calculate the stopping distance of the train under consideration: S = (V + V0) * t / 2 = (0 + 15) * 30/2 = 225 m.

Answer: The train was braking with an acceleration of -0.5 m / s2; its stopping distance was 225 m.