The driver of a train travelling at 40 ms-1 applies the brakes as a train enters a station. The train slowsdown at a rate of 2 ms-2. The platform is 400 m long. Will the train stop in time?
Initial Speed = u = 40 ms-1
Acceleration = a = - 2 ms-2 (Retardation, hence negative)
Final Speed = v
Now, s = Distance train travels before stopping
Now, we know from the equations of motion that,
s = 400 m
So, the train covers 400 m before stopping.
Also the length of platform = 400 m.
So, the train stops in time.