Question

A particle is dropped from the tower it is found that it Travels 45 metre in last second of its journey find out the height of the tower

Answer 1

let the time taken by particle to travel the whole height be n second then in the nth second it is travelling 45 metre.

distance traveled in nth second =
u+1/2(2n-1)a
where u= initial velocity=0
a=g=10
distance traveled=45metre

45=1/2×10(2n-1)
n=5 sec

so the particle traveled h height in 5 second

therefore
h=ut+1/2at^2
h=0+1/2×10×(5)^2
h=125metre