Find drop time t = √(2h / g) and impact speed v = √(2 g h) from rest, with no air drag.
| Time (s) | – |
| Impact speed (m/s) | – |
Use this calculator for an object released from rest through height h in a uniform gravitational field. Time is t = √(2h / g) and impact speed is v = √(2 g h). Air resistance is ignored, so the speed is overstated for light objects such as paper or feathers. On Earth g is about 9.81 m/s².
A 20 m drop at g = 9.81 m/s² takes about 2.02 s and hits at about 19.8 m/s. Height and g must be greater than zero. This is not a thrown-object or parachute model.
Height (m): Fall distance in metres.
g (m/s²): Gravitational field. 9.81 on Earth, about 1.62 on the Moon.
Time (s): Time from rest to impact.
Impact speed (m/s): Speed at the bottom, no drag.
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