Free Fall Calculator
Calculate free fall time, height, velocity, and acceleration in vacuum with step-by-step kinematics.
What Is Free Fall?
Free fall describes motion under gravity alone, with no air resistance. Near Earth's surface, objects accelerate at about 9.81 m/s² regardless of mass (in vacuum). This calculator solves height, time, impact velocity, or gravity from the kinematic equations of uniformly accelerated motion.
Free Fall Equations
$$h = \frac{1}{2}gt^2, \quad v = gt, \quad v = \sqrt{2gh}$$Height \(h\) is in meters, time \(t\) in seconds, velocity \(v\) in m/s, and gravity \(g\) in m/s². Dropping from 100 m on Earth: \(t = \sqrt{2 \times 100 / 9.80665} \approx 4.52\) s and \(v = \sqrt{2 \times 9.80665 \times 100} \approx 44.3\) m/s.
Assumptions
The model ignores air drag, initial velocity, and variation of \(g\) with altitude. For real-world drops where drag matters, use the Free Fall Air Resistance Calculator.
Related tools: G-Force Calculator and Free Fall Air Resistance Calculator.
Frequently Asked Questions
Do heavier objects fall faster in free fall?
No, in vacuum all objects fall with the same acceleration g regardless of mass. Air resistance is what makes light objects appear to fall slower in air.
What is impact velocity?
Impact velocity is the speed just before the object hits the ground. In free fall from rest it equals gt or √(2gh).
Can I solve for gravity on another planet?
Yes. Choose "Solve for gravity" and enter the drop height and measured fall time. The result gives local gravitational acceleration.
Does this include initial upward or downward velocity?
No. The calculator assumes the object starts from rest. Thrown objects need a projectile motion model with initial velocity.
Why is Earth's g about 9.81 m/s²?
It comes from Newton's law of gravitation and Earth's mass and radius. The exact value varies slightly with latitude and altitude.
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