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 m s−2.Find:(i) the velocity after 10 s, and (ii) the time taken by the train to come to rest.

Solution

## Equation to be applied  " v = u - a×t ", v is final velocity, u is initial velocity, a is retardation and t is time.   Velocity at the time of applying break = 90 km/h  = 90 km/h × (5/18) = 25 m/s    (1) velocity after 10 s :-   v = 25-(1/2)×10 = 20 m/s   (2) time to come to rest :-  0 = 25-(1/2)×t  , solving for t ,  we get  t = 50 s

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