a stone is dropped from the top of a tower travels 35m in last second of journey. the height of the tower is.

Dear student, 
s= ut + (1/2)ft2
in the last second,  t= 1 second,   s= 35m, and f=g= 9.8 m/s2
so,
35 = u + 0.5×9.8
=》 u= 35 -4.9 = 30.1 m/s.
now initial velocity,  u1= 0,  final velocity,  u= 30.1 m/a,
Now,  u2 - u12 = 2fs
=》 s = [(30.1)2 - 0]/(2×9.8)
=》 s = 46.225 m
initial velocity u1=0, final velocity 
so height of the tower
H= 35+46.225 =  81.225 m

Regards. 

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