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.

Answer 1

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