Question

A passenger train is moving at 5m/s.An express train is travelling at 30m/s,on the Same track and near side of the passenger train at some distance.The driver in express train applied brakes to avoid collision.If the retardation due to brakes is 4m/s^2,find the time in which the accident is avoided after the application of brakes?

Answer 1

do not know it bro I could not understand

Answer 2

Answer:

Initial relative velocity of the express train w.r.t. the passenger train,

u ep =u e -u p =30-5=25 ms^ -1

Final relative velocity of the express train w.r.t the passenger train,

v ep =0 (because express train comes to rest)

From first equation of motion

v ep =u ep -at

or 0 = 25 - 4t

or 4t = 2 ^ 5

or t = 6.25s