Question

a body Falls freely from the top of a tower it covers 36% of the total height in the last second before striking the ground the height of the Tower is(g=10ms)

Answer 1

Let H be the height of the building and t be the time to fall through this height H. 

Then H = ½ g t^2 = 5 t^2. ----------------- (1) 

In (t-1) second the distance traveled is 1 - 0.36 H = 0.64 H. 

0.64 H = 5 (t-1)^2.---------------------------(2) 

(2) / (1) gives 0.64 = (t-1)^2/ t^2 

Or 0.8 = (t-1) / t 

Solving we get t= 5 second. 

Using (1) we get H = 125 m.

Answer 2

Let the total height be H
As body is free fall then distance covered in last 1 sec = 5m = 36% of total height H
as 36/100 of H = 5
therefore H = 5× 100/36
= 500/36
= 125/9
= 13.88m or 13.9 m