Calculators
Well Depth from Fall Time
Depth of a well or a cliff from the fall time of a stone
Result
Enter the values and the result will appear here.
A caveat
Air resistance is ignored: it is accurate for the first 3–4 seconds, while in a longer fall the real speed is noticeably lower. If you timed the splash by sound, subtract the time the sound needs to travel back, or the depth will come out too large.
Formula
g = 9.81 m/s² is the acceleration of free fall, t is the fall time, h is the depth, v is the speed at the end.
A finished calculation is added to the history automatically.
History
Entries: 0Nothing yet — finished calculations will appear here by themselves.
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Частые вопросы
Which formula gives the depth?
h = g·t² / 2, where g = 9.81 m/s² is the acceleration of free fall and t is the fall time. In 3 seconds a stone falls about 44 metres.
Why is the depth too large when I listened for the splash?
The time includes the sound travelling back up. Subtract it (the depth divided by 343 m/s) or time only the stone in flight.
Is air resistance taken into account?
No. For the first 3–4 seconds of a fall the error is small; in a longer fall the real speed is noticeably lower than calculated.
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