Board Thread:General Grimm Discussion/@comment-37854251-20181218142610/@comment-25593389-20190208004308

Well, if it took 10 secs for the sound to come back 'on screen' then it means that the brick touched the ground between 8 and 9 secs after he dropped it (closer to 9 secs)...

Because you basically forgot to take into account the time it would take for the sound to come back, the sound travels at around 340 m/s, so you should also take that in account into your calculations.

For something to fall around 390-400 meters, it takes around 9 secs, for the sound to travel back from 390m, it takes 1,15 secs.

So you should shorten you approximation, by at least a 100 meters, depending on other conditions, it might not be wrong to shorten it even a bit more.