Question

A train is moving with a velocity of 90 km h^-1 . It is brought to stop by applying the brakes which produce a retardation of 0.5 ms^-2 Find :
(i) The velocity after 10 s , and
(ii) the time taken by the train to come to rest .

Answer 1

Initial velocity u = 90 km/h = 25 m/s

Final velocity v = 0 m/s

Acceleration a = -0.5 m/s²

 

(i) Let 'V' be the velocity after time t = 10 s

Using the first equation of motion,

v = u + at

We get,

V = 25 + (-0.5) (10) m/s

V = 25 - 5 = 20 m/s^-1

(ii) Let t' be the time taken by the train to come to rest.

Using the first equation of motion,

v = u + at

We get,

t' = [(0 - 25)/ (-0.5)] s

t' = 50 s