 # A train stopping at 2 stations 4 km apart takes 4 min on the journey from one of the station to the other.Assuming that it first accelerates with uni.acceleration x and then that of uniform retardation y, prove that (1/x)+(1/y)=2  Badiuddin askIITians.ismu Expert
148 Points
12 years ago

Dear Chilukuri

let t1 is time of acceleration and s1 is distance covered in this time .v is the velocity after time t

let t2 is time of retardation and s2 is distance covered in this time .

v2=02-2xs1

s1=v2/2x..............1

v=0+xt1

v/x=t1 ..................2

and  0=v-yt2

t2=v/y .................3

02=v2-2ys2

s2=v2/2y..............4

1/x  +1/y  =(t1+t2)/v

=4/v..........5

s1+s2 =v2/2(1/x +1/y)

4=v2/2(1/x +1/y)

or (1/x +1/y) =8/v2

put value of v from equation 5

1/x +1/y  =2

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