A person sitting on the top of a tall building is dropping balls at regular intervals of one second. Find the positions of the 3rd, 4th and 5th ball when the 6th ball is being dropped.

Answer

A, B, C, D

Explanation

For every ball
`u=0, a=g=9.8 m/s^2 `4th ball moves for 2 sec. 5th ball for 1 sec and 3rd ball for 3 sec when 6th ball is being dropped. For 3rd ball
`t=3 sec
:. S_1 = ut+ 1/2 atI^2ltbrge0+1/2 9.8(3)^2
=44.1 m` below the top. For 4th ball
t=2 sec
` :. S_2 = 0+1/2 g^2=1/2xx9.8 xx(2)^2
=19.6`m below the top [u=0]
for 5th ball t=1 sec
`:. S_3 = ut+ 1/2 at^2
=0+ 1/2 xx 9.8x t^2
=4.9` m below the top.