Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

A stone is dropped into a 40m deep well. The sound of the splash is heard 2.95 seconds after the stone is dropped. Find the speed of sound.

share|cite|improve this question

closed as too localized by Qmechanic Feb 15 '13 at 15:23

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

What have you tried? Where are you stuck? Please be sure to read:… – Bernhard Nov 28 '12 at 6:51
up vote 0 down vote accepted

Let, $t$=time taken by the stone; $T$=Time taken by the sound(both are in second) $d$=depth of the well and $s$=velocity of the sound

Use the following equations:

$d=1/2 gt^2$ (For stone)

$d=sT$ (For sound)


Finally, put $d=40 m$, solve for $t$. Find out $T$ and hence $s$ i.e the speed of sound.

share|cite|improve this answer
I don't see how the second equation $d = \frac{1}{2}gt^2$ is valid for sound. The second equation is for the stone which you have already mentioned before. There should be just 3 equations. – Debangshu Nov 28 '12 at 7:09

Not the answer you're looking for? Browse other questions tagged or ask your own question.