Free Fall Simulation
Drop objects from any height and watch gravity do its work. A heavy ball and a light feather fall side by side — with no air resistance, they always land together, no matter their mass.
Free Fall Simulation
The Physics Behind This Simulation
With no air resistance, every falling object accelerates at exactly the same rate — gravitational acceleration, g — regardless of its mass. That's why the ball and the feather in this simulation always hit the ground at the same instant. The motion follows three equations, all special cases of SUVAT with initial velocity u = 0:
Where h is the height fallen, g is gravitational acceleration, t is the time elapsed, and v is the velocity at that time. This is the free-fall special case of the general SUVAT equations — the same relationships this site's SUVAT Equations Calculator solves for any combination of known values.
Things to Try
Same time, any mass
Drop the ball and feather together at any height. They always land at the same instant — mass genuinely does not affect fall time in a vacuum.
The real hammer-and-feather test
In 1971, Apollo 15 astronaut David Scott dropped a hammer and a feather together on the airless Moon — and they landed together, exactly as this simulation predicts.
Switch to the Moon
Change gravity to 1.62 m/s² and drop from the same height. Fall time roughly doubles, and impact velocity drops to about 40% of its Earth value.
Why a real feather falls slower
On Earth, air resistance — not mass — is what makes a feather drift down slowly. This simulation ignores air resistance entirely, which is why it matches the Moon experiment, not everyday experience in air.