In free fall the only force on an object is gravity. Drop something from rest and it speeds up at g = 9.81 m/s². This free fall calculator finds how long the fall takes and how fast the object is moving when it lands.
The answers ignore air resistance, which is fine for short drops of dense objects. Light or fast-moving objects (a feather, a skydiver) reach a terminal velocity and fall more slowly than this.
| Height of fall (h) | 20 m |
| Time to fall (s) | 2.01962 |
| Impact speed (m/s) | 19.8057 |
| Impact speed (km/h) | 71.3005 |
It takes 2.01962 s to land and hits the ground at 19.8057 m/s (71.3005 km/h).
Try this example →| Height of fall (h) | 20 m |
| Acceleration due to gravity (g) | 1.62 m/s² |
| Time to fall (s) | 4.96904 |
| Impact speed (m/s) | 8.04984 |
| Impact speed (km/h) | 28.9794 |
On the Moon it takes 4.96904 s and lands at only 8.04984 m/s.
Try this example →No. Galileo showed that, without air, all objects fall with the same acceleration. A heavier object has more weight, but also more mass to accelerate, and the two cancel in a = F ÷ m = mg ÷ m = g.
Distance fallen h = ½gt². Rearranged, time t = √(2h/g) and impact speed v = √(2gh).
Standard gravity is 9.80665 m/s², usually rounded to 9.8 or 9.81 m/s².
About 4.5 seconds, reaching about 44 m/s (160 km/h), ignoring air resistance.
The constant speed reached when air resistance equals weight. A skydiver's is about 55 m/s (200 km/h).