How can I calculate the depth of a well using free fall and distance equations?

[Sunsethorizon]

Homework Statement

A stone falls from top of a well, 10 seconds later sound of water splash reaches the top of the well. How deep is the well?

g=9.82m/s², v_sound=340m/s , t=10s

2. Homework Equations
s=vt , v=a₀+at , s=v₀t+1/2at²

3. The attempt at a solution
I'm stuck. I know the distance of the soundwaves traveling from the bottom to the top of the well is given by s=vt. And the distance the rock travels is given by s=v₀t+1/2at².

Do i try figure out for how long the rock travels before hitting the bottom?, Or are equations supposed to be merged? Please point me in the right direction :)

 

[.Scott]

You already have s=v0t+1/2at^2
In this case, the initial velocity is 0, so the distance is s=1/2at^2.
For the sound return, s=340m t.
So you need your two s's to be equal and your two t's to add to 10 seconds.

 

[scottdave]

Use t in one of the equation for motion, and (10 - t) in the one for sound. Set the distances equal to each other. Once you have t, you can find the distance in the usual fashion.

 

[Sunsethorizon]

Thank you! Excellent help gentlemen, i fully understand now.