A train traveling at a certain speed must pass after the start of braking until the stop is 200 m

A train traveling at a certain speed must pass after the start of braking until the stop is 200 m at what speed the train moves before braking if it lasted 20 seconds.

These tasks: S (distance traveled by the train under consideration to a full stop) = 200 m; t (deceleration time) = 20 s.

The speed with which the train in question was moving before braking can be expressed from the formula: S = (V + V0) * t / 2 = V0 * t / 2, whence V0 = 2S / t.

Let’s calculate: V0 = 2 * 200/20 = 20 m / s or 72 km / h.

Answer: Before braking, the train in question was moving at a speed of 20 m / s (72 km / h).