Calculate the time taken by the first ball to travel the maximum height:
v=0 at the maximum height
During the three-second of the journey, the ball travels a distance of
Let the height of the tower be h. If t is the time taken by the second ball to reach the ground. The total downward journey by the first ball is for (t+4-3) sec, that is t+1 sec
During t+1 sec the first ball travels a distance of 45+h
45+h =0.5 g (t+1)2......(2)
Also
h= 0.5gt2........(2) (time taken by second ball)
from 1 and 2
45+h=0.5gt2+gt+0.5g
45+0.5gt2=0.5gt2+10t+5
40=10t
t=4sec
h=0.5 x 10 x 16=80m
The height of tower= 80 m