3.75 m

 

when !st on floor..5th is falling it means first take 2t sec(say)

2t=root of( 2h/g)

t=1/2 sec...

this means...third drop has fallen by 1/2 sec

h=1/2gt(sq.)=1.25 from top

 

let drops fall after time interval t and first drop falls at t=0
second drop falls after time t
third after 2t
fifth after 4t

clearly from the ques
time taken by first drop to reach ground = 4t
using second eqn of motion and putting u = 0 for first drop
5 = 1/2g*(4t)^2
putting g= 10
u get t = 1/4

for third drop , time = 2t =1/2
s= 1/2 * 10 * 1/4
= 10/8 = 1.25 from tap

from ground ht = 5 - 1.25 = 3.75
Correct if i m wrong
rate if this helps u...

time taken for each drop to reach to the ground:

 

h=1/2gt²

 

5 = 0.5gt²

 

t = 1 sec

 

when 5th drop starts to fall, 1st reaches the ground. So the rate of falling of drops is 4 balls per sec (or 1 ball per 0.25 sec)

so when the third ball would have started, time passed would be 0.5 sec

 

after that 0.5 sec more have passed.. so the third is now in the air.

 

and the distance traversed by it is:

 

y=1/2gt²

y=1/2(10)(0.5)²

y=1.25m

 

thus, the height from the ground is 3.75m