Suppose the speed of sound is c, and gravity is g. If you throw a rock from an initial height h0 and with an initial velocity v0 the height h(t) of the rock after time t is

h(t)=−g2t^2+v0t+h0.
(The height is negative when the rock is below ground level. Thus you can think of depth as negative height.)
Suppose you throw the rock down a well and hear the impact after t seconds. Then the depth of this well is
d= ????.
(Your answer will be a mathematical expression involving t, g, and c.)
Set up and solve a quadratic equation.

3 answers

First of all, your equation contains a typo, it should say:
h(t)= (−g/2) t^2+v0t+h0

secondly, what units are you using?
thirdly, did you drop the rock or did you give it a downwards velocity?

let me know before I can answer your question.
Just noticed that Steve answered your question yesterday.
http://www.jiskha.com/display.cgi?id=1468295145

Why are you repeating it? (this time with a typo)
thx could not find it