Free Fall
Calculate free fall time, final velocity, and impact speed from height using t = sqrt(2h/g) and v = sqrt(2gh) with Earth gravity g = 9.80665 m/s². Free online physics calculator for students and engineers.
About This Calculator
The Free Fall Calculator computes the time it takes for an object to fall from a given height under the influence of Earth's gravity, along with its final velocity and impact speed. This calculator is ideal for physics students, engineers, and anyone curious about the dynamics of falling objects. It assumes no air resistance (vacuum conditions), following the classic free fall equations derived from Newtonian mechanics.
The calculator uses the standard free fall formulas: t = √(2h/g) for fall time, v = √(2gh) for final velocity (in m/s), and multiplies by 3.6 to convert to km/h. The gravitational acceleration is set to the standard Earth value of g = 9.80665 m/s². All objects in free fall experience the same acceleration regardless of mass, as demonstrated by Galileo's legendary experiments from the Leaning Tower of Pisa.
How Free Fall Works
In free fall, an object moves under the influence of gravitational force only. The absence of air resistance means that a feather and a brick dropped from the same height would hit the ground simultaneously. This principle was famously proven on the Moon during the Apollo 15 mission by astronaut David Scott, who dropped a hammer and a feather and watched them land at the same time.
Regional Notes
The formulas used are universal physics equations that apply worldwide. The standard value g = 9.80665 m/s² is the internationally accepted gravitational acceleration at sea level. Slight local variations exist due to altitude and latitude, but the standard value is accurate for most practical purposes across all regions.
Frequently Asked Questions
What is free fall in physics?
Free fall is the motion of an object under the influence of gravitational force only, with no other forces like air resistance acting on it. In a vacuum, all objects fall with the same acceleration regardless of their mass.
What is the value of g used in this calculator?
This calculator uses the standard Earth gravitational acceleration g = 9.80665 m/s² (32.174 ft/s²). This value represents the average acceleration due to gravity at sea level.
How do you calculate free fall time from height?
Free fall time from height is calculated using the formula t = sqrt(2h/g), where h is the height in meters and g is the gravitational acceleration (9.80665 m/s²). For example, from 100 meters, the fall time is about 4.52 seconds.
How do you calculate free fall velocity?
Free fall velocity is calculated using v = sqrt(2gh), where h is the height and g is gravitational acceleration. For a fall from 100 meters, the impact velocity is approximately 44.3 m/s or 159.5 km/h.
Does free fall depend on the mass of the object?
No, in a vacuum (no air resistance), all objects fall at the same rate regardless of mass. This was famously demonstrated by Galileo and later by Apollo 15 astronaut David Scott who dropped a hammer and feather on the Moon.
What is the difference between free fall and terminal velocity?
Free fall assumes only gravity acts on the object. In reality, air resistance increases with speed until it balances gravity, at which point the object stops accelerating and reaches terminal velocity. For a skydiver, terminal velocity is about 53 m/s (190 km/h) in belly-down position.
What was the highest free fall in history?
The highest free fall was performed by Dr. Alan Eustace in 2014, who jumped from 135,908 feet (41,425 meters). His fall lasted 15 minutes and he reached speeds exceeding 800 mph (1,287 km/h), breaking the sound barrier.