Question

if the distance travelled by a freely falling body in the last second of its journey is equal to the distance travelled in the first 2 seconds, time of descent to the body is

Answer 1

The distance travelled by the free falling body in 2 second is 1/2 * 10*(2)² = 20 m
that is equal to the distance traveled in last second

then, 20 m = u + 1/2*10*(1)²
or, u = 15 meter /.second

then v = u + at
or v = 15 + 10
or v = 25 m /.second

now total time is
v = u + at
25 = 0 + 5t
t = 5 second

Answer 2

Answer:

It will be 2.5 sec

Explanation:

Dist travelled in first 2 sec= 1/2gt²

and dist travelled in last sec is u+g/2 (2t-1)

Equating both

We get t°2.5 sec