A body falls freely from a height of 125m `(g = 10 m//s^2)` after 2 sec gravity ceases to act Find the time taken by it to reach the ground?

Explanation

(1)Distance covered in 2s under gravity
`s_1=1/2 "gt"^2 =1/2(10)2^2`=20 m
velocity at the end of 2s
V=gt=(10)2=20m/s
Now at this instant gravity ceases to act
`rArr` velocity by here after becomes constant.
The remaining distance which is 125-20=105 m is covered by the body with constant velocity of 20 m/s .
Time taken to cover 105 m with constant velocity is given by ,
`t_1=S/V rArr t_1=105/20`=5.25s
Hence total time taken to reach the ground
=2+5.25=7.25 s