question_answer 27)

A train is travelling at a speed of 90 kmh-1. Brakes are applied so as to produce a uniform acceleration of -0.5 ms-2. Find how far the train will go before it is brought to rest?  

Answer:

Here, initial speed, u = 90 kmh-1 =   = 25 ms-1 Acceleration, a = - 0.5 ms-2 Train brought to rest, so final speed, v = 0 From third equation of motion, v2 = u2 + 2as 0 = (25)2 + 2 x 0.5 x s 0 = 625 - s s = 625 m