Calculate free fall distance, time, and velocity. Solve for any variable with optional initial velocity, planetary gravity comparison, and distance-time tables.
Free fall describes motion under the sole influence of gravity, with no air resistance. Starting from rest, an object near Earth's surface accelerates at about g = 9.81 m/s², gaining roughly 35 km/h of speed every second.
The core equations d = ½gt², v = gt, and v² = 2gd are the basic tools for relating distance, time, and velocity in the ideal case. They are useful whenever you want to solve one part of the motion from the other two.
This calculator solves for any unknown distance, time, or velocity, supports an initial downward velocity, allows custom gravitational acceleration, and compares results across different celestial bodies.
Free-fall problems often come down to choosing the right equation for the known quantity. This calculator keeps the distance, time, and velocity forms together so the same setup can be checked from multiple angles without redoing the algebra each time.
Free Fall Equations (from rest): d = v₀t + ½gt² v = v₀ + gt v² = v₀² + 2gd Solving for time from distance: t = (−v₀ + √(v₀² + 2gd)) / g Specific impact energy: E/m = gd Where: d = distance (m), t = time (s) v₀ = initial velocity (m/s), v = final velocity (m/s) g = gravitational acceleration (9.81 m/s² on Earth)
Result: t = 2.019 s, v = 19.81 m/s (71.3 km/h)
Dropping from 20 m on Earth: t = √(2 × 20 / 9.81) = 2.019 s. Final velocity: v = 9.81 × 2.019 = 19.81 m/s = 71.3 km/h.
Free fall is the simplest gravitational motion: constant downward acceleration with no other forces. The resulting parabolic distance-time relationship (d ∝ t²) means an object covers progressively more distance each second. After 1 s it has fallen 4.9 m; after 2 s, 19.6 m (not 9.8); after 3 s, 44.1 m.
The velocity increases linearly: about 9.81 m/s added per second. After 4 seconds, a dropped object on Earth is moving at ≈ 39 m/s (141 km/h). This relentless acceleration is why even moderate heights can produce dangerous impact speeds.
In practice, air resistance always exists and grows with speed. For a compact, heavy object (bowling ball, rock), free fall equations are accurate for drops of a few meters. For lighter objects or higher drops, air resistance becomes significant. A skydiver reaches terminal velocity (where drag equals gravity) after about 12 seconds of free fall.
Galileo's insight that all objects fall at the same rate was revolutionary. It contradicted Aristotle's claim that heavier objects fall faster, which had been accepted for nearly two millennia. This principle — along with the parabolic trajectory of projectiles — laid the foundation for Newton's laws of motion and the entire field of classical mechanics.
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No. In a vacuum, all objects fall at the same rate regardless of mass. This was demonstrated dramatically on the Moon by Apollo 15 astronaut David Scott, who dropped a hammer and feather simultaneously — they hit the ground together.
Free fall by definition assumes no air resistance. For real-world scenarios with drag (skydiving, parachutes), see the free-fall-air-resistance calculator. Free fall equations work well for dense objects over short distances.
Felix Baumgartner jumped from 39 km altitude in 2012, reaching 1,357 km/h (Mach 1.25) during his free fall phase. Alan Eustace later broke the altitude record at 41.4 km in 2014.
Earth's surface gravity varies from about 9.78 m/s² at the equator to 9.83 m/s² at the poles due to Earth's rotation and equatorial bulge. The standard value is g = 9.80665 m/s².
Yes, for downward throws. Set the initial velocity to the throw speed. For objects thrown upward, the equations still work but you need to handle the upward phase separately (this calculator assumes downward motion).
Because objects accelerate during free fall. In the first half of the fall time, the object covers only 25% of the total distance. The remaining 75% is covered in the second half of the time, when the object is moving faster.