a stone is dropped into a well with no initial velocity then the splash is heard in 4.5 sec then second stone is thrown with initial velocity "u " then the splash sound is heard after 4 sec what is the initial velocity? Take g =9.81

If nobody is around to hear the rock hit the water, did it make a sound?

If nobody is around to hear the rock hit the water, did it make a sound?
Yeah yeah that mean u may even say that there is nothing like atmosphere but u can discard will u ?

Homework rules posted on this site clearly state we don't hand you answers... you must furst attempt the work and demonstrate what you got before we offer any help with what you did wrong.

Homework rules posted on this site clearly state we don't hand you answers...you must furst attempt the work and demonstrate what you got before we offer any help with what you did wrong.

kk
I assumed the time taken by the stone to reach water as "t1" and sound wave to reach the observer as "t2"
hence for 1st condition I took
t1+t2=t... eq1
i.e. t1+t2=4.5... eq1
for stone
u=0 m/s, s= -d(considering upward direction as +ve) m ,a=g=9.81 sec, t= t1sec
s=ut+1/2at^2
for sound
u=330 m/s, a=0, t=t2 sec, s=d m
using the same formula as above: s=ut+1/2at^2
then I got d as d= 81.407m how get 2nd con I used the same steps to solve
but I got the desired one as my ans i.e. u= 3.025m/s where a the actual ans is 5.205m/s