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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.

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What have you tried? Where are you stuck? Please be sure to read: meta.physics.stackexchange.com/questions/714/… – Bernhard Nov 28 '12 at 6:51

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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)

$t+T=2.95$

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

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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

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