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Free Fall Calculator

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Enter a drop height to find how long an object falls and how fast it's moving when it lands, ignoring air resistance.

Free Fall Calculator

Live
Fall time
2.02 s
Final velocity
19.8 m/s
Assumes no air resistance - real falling objects (especially light or large-surface-area ones) fall somewhat slower due to drag.

The formulas

Fall time = sqrt(2 x Height / Gravity) Final velocity = Gravity x Fall time
Example

An object dropped from 20 meters on Earth: time = sqrt(2x20/9.8) ≈ 2.02 seconds, hitting the ground at about 19.8 m/s.

Step-by-step guide

  1. Enter the drop height.
  2. Select the gravity value for your context - Earth by default.
  3. Read the fall time and final velocity.

Why heavier and lighter objects fall at the same rate (in theory)

Ignoring air resistance, all objects - regardless of mass - fall at exactly the same rate under gravity, a famous result often attributed to Galileo's (likely apocryphal) Leaning Tower of Pisa experiment, and dramatically confirmed on the airless Moon when astronauts dropped a hammer and feather side by side and watched them land together. In real-world conditions on Earth, air resistance meaningfully slows lighter or larger-surface-area objects (like a feather) more than dense, compact ones (like a hammer), which is why this idealized result doesn't always match everyday experience.

Common mistakes

Expecting this idealized result to exactly match a real-world drop of a light or large-surface-area object - air resistance meaningfully affects those cases, unlike this no-air-resistance calculation.
Assuming the object's mass affects fall time in this ideal formula - mass doesn't appear in either equation, since (ignoring air resistance) all objects fall at the same rate regardless of mass.

Frequently asked questions

Does a heavier object really fall at the same rate as a lighter one?

Yes, in a vacuum or when air resistance is negligible - mass doesn't appear in the free fall equations at all. In real air, a dense, compact object experiences relatively less air resistance and falls closer to this ideal prediction than a light, spread-out object like a sheet of paper.

Why does the Moon experiment (hammer and feather) work?

The Moon has essentially no atmosphere, so there's no air resistance to slow the feather down disproportionately - both objects fall purely under gravity's influence and land at exactly the same time, exactly as this formula predicts.

Does this work for objects thrown downward, not just dropped?

No - this calculator specifically assumes the object starts from rest (a simple drop, zero initial velocity). An object thrown downward with initial speed would reach the ground faster, requiring a more complete kinematics equation.

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