Table of Contents
What Is Free Fall?
Free fall is the motion of an object under the sole influence of gravity, with no air resistance. All objects in free fall accelerate at the same rate regardless of mass, as demonstrated by Galileo and later explained by Newton. On Earth's surface, this acceleration is approximately 9.81 m/s2.
Free fall is idealized motion that ignores air resistance. For dense, compact objects over short distances, it is an excellent approximation. For light objects or long falls, air drag becomes significant and terminal velocity limits the speed. The free fall equations form the foundation of kinematics and are essential for physics education and engineering.
Formulas
Examples
| Height | Time | Impact Speed |
|---|---|---|
| 1 m | 0.45 s | 4.43 m/s (16 km/h) |
| 10 m | 1.43 s | 14.0 m/s (50 km/h) |
| 100 m | 4.52 s | 44.3 m/s (159 km/h) |
| 1000 m | 14.3 s | 140 m/s (504 km/h)* |
*Without air resistance. Actual terminal velocity for a human is about 55 m/s.
FAQ
Do heavier objects fall faster?
In vacuum, no. All objects experience the same gravitational acceleration regardless of mass. In air, denser objects fall faster because air resistance is proportional to surface area while gravitational force is proportional to mass. A bowling ball and feather fall at the same rate in vacuum (demonstrated on the Moon by Apollo 15).
What is g exactly?
Standard gravity is defined as 9.80665 m/s2. Actual g varies with latitude (9.78 at equator to 9.83 at poles), altitude, and local geology. GPS satellites and gravimeters measure these variations with extreme precision for geodesy and mineral exploration.
How fast do skydivers fall?
Terminal velocity for a typical skydiver in belly-down position is about 55 m/s (200 km/h). Head-down position reaches about 90 m/s (320 km/h). Felix Baumgartner reached 373 m/s (1,342 km/h) falling from 39 km altitude where air is very thin.