The train moving from the station with an acceleration of 0.4 m / s ^ 2 covered a distance of 0.8 km. What speed did the train reach?

Given: V0 (initial speed) = 0 m / s; a (acceleration of a given train) = 0.4 m / s2; S (distance traveled from the station) = 0.8 km (SI S = 800 m).

We express the sought speed that the given train has reached from the formula: S = (V2 – V02) / 2a = (V2 – 02) / 2a, whence V = √ (2a * S).

Calculation: V = √ (2 * 0.4 * 800) = 25.3 m / s.

Answer: After passing 800 m, the speed of the given train will be 25.3 m / s.