Calculate Stone in Well

Stopwatch and calculator for the fall time and fall distance of a stone, from release to arrival, e.g. to determine the depth of a well (the distance to the water level). When you let go, tap start and when you hear the sound of the rock dropping, tap stop (same button).

This calculator can also be used without the stopwatch, simply enter one of the three values and press Calculate. The free fall without air resistance is calculated. For a round stone, this is a good approximation up to a fall duration of around 10 seconds, which corresponds to almost 500 meters, after which the air resistance becomes significant and the calculated values are too high. For stones that are not quite round, air resistance becomes relevant a little earlier, but it is unlikely that you will find wells that deep anyway, and throwing stones down several hundred meters should be avoided for safety reasons anyway. Even at low heights, the following applies: before you drop stones from anywhere, you must of course pay attention to where they will land, so that you do not hurt anyone or break anything! If the surface on which the stone lands is not flat and large enough, then it will roll further down, and this must also be taken into account.

If the free fall takes place in a vacuum, then the shape, mass and density of the object do not play a role, otherwise air resistance comes into play and makes the calculation complicated. Air resistance can be ignored at low speeds, aerodynamic shapes, high mass and high density if you do not need the result to be accurate to several decimal places. This applies to the stones mentioned above, even better to metal balls and somewhat less to things made of wood. The exact limit at which you have to take air resistance into account is difficult to determine. For the calculation, see Fall Velocity with Air Resistance.

Physics commonly uses SI units. Here is a calculator to convert units.