A train is moving with 72 kmh−1speed. The driver applies the brakes and the train decelerates with 1.3 ms−2and takes 25 seconds before it stops. Calculate the distance covered by the train after applying the brakes

Answer 1

Given values are
vi=72kmsec−1=20msec−1
vf=0ms-1
a=−1.3msec−2
t=25sec
Use second equation of motion to find traveled distance before stopping.
S=Vit+1/2 at2
S=(20)x(25)+1/2(-0.3)(25)2
S=93.75m

Answer 2

Vi = 72000 meters /3600 seconds = 20 m/s
Vf = 0
a = -1.3 m/s^2
v = Vi + a t
0 = 20 -1.3 t
t = 15.4 seconds , Not 25 seconds
d = average speed * time = 10 m/s * 15.4 s = 154 meters