Mon July 16, 2012 By: Inder Kumar

brakes are applied to a train traveling at 72 km/h after passing 200m its velocity reduced to 36 km/h at same rate of retardation how much further will it go before it goes to rest solution please

Expert Reply
Tue July 17, 2012
Initial velocity, u = 72 kmph = 20 m/s
Final velocity, v = 36 kmph = 10 m/s
displacement, s = 200 m
let acceleration be a.
using 3rd equation of motion,
a = (v2-u2)/2s = -3/4 m/s2
now final velocity =0 m/s
let final displacement from this position be s
again using 3rd equation of motion,
s = (v2-u2)/2a = 200/3 m
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