A body falls freely from the top of a tower. It covers 36% of the total height in the lkast second before striking the ground level. The height of the tower is

Options

A. 50 m
B. 75 m
C. 100 m
D. 125 m

Answer

D

Explanation

Let height of tower is h and body takes t time to reach to ground when it fall freely.
` therefore h = 1/2 "gt"^2`
In last second body travels = 0.36 h
It means in rest of the time i.e. in ( t-1) sec it travels
= h - 0.36 h = 0.64h
Now applying equation of motion for (t – 1) sec
`0.64h = 1/2 g(t - 1)^2` .....(ii)
From (i) and (ii) we get, t = 5sec and h = 125 h