Free Fall Calculator: Calculate Velocity, Time & Height in Free Fall

Calculate free fall motion: velocity, time, and height using gravity acceleration. Free online physics calculator for kinematics problems with step-by-step solutions and multiple unit support.

Free Fall Calculator

Calculate free fall motion: velocity, time, height using gravity acceleration

Instructions

  • • Enter gravity (default: 9.80665 m/s² for Earth)
  • • Enter initial velocity (optional, defaults to 0 for true free fall)
  • • Provide at least 2 of: final velocity, time, or height
  • • Leave the value you want to calculate empty
  • • Formulas: v = v₀ + gt, h = v₀t + (1/2)gt², v² = v₀² + 2gh
  • • Select your preferred units for each measurement
  • • The calculator automatically converts between different units

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Understanding Free Fall: Motion Under Gravity

Free fall is a fundamental concept in physics that describes the motion of an object falling solely under the influence of gravity, with no air resistance or other forces acting upon it. Whether you're studying kinematics, solving physics problems, or analyzing projectile motion, understanding free fall is essential. Our Free Fall Calculator makes it easy to calculate velocity, time, or height using the standard free fall equations: v = v₀ + gt, h = v₀t + (1/2)gt², and v² = v₀² + 2gh.

In true free fall, the only force acting on the object is gravity, which provides a constant downward acceleration. On Earth, this acceleration is approximately 9.80665 m/s² (32.174 ft/s²), though it varies slightly with location and altitude.

How to Use Our Free Fall Calculator

Our Free Fall Calculator is designed for simplicity and accuracy:

  1. Enter Gravity: Input the gravitational acceleration (default: 9.80665 m/s² for Earth)
  2. Enter Initial Velocity (Optional): If the object starts with an initial velocity, enter it (default: 0 for true free fall)
  3. Provide Known Values: Enter at least 2 of: final velocity, time, or height
  4. Calculate: Leave the value you want to calculate empty and click Calculate

The calculator uses the fundamental free fall equations to solve for the missing variable.

Understanding Free Fall Formulas

Free fall motion is described by three key equations:

1. Velocity-Time Equation

v = v₀ + gt

Where: v = final velocity, v₀ = initial velocity, g = gravity, t = time

This equation calculates the final velocity after a given time. If the object starts from rest (v₀ = 0), the equation simplifies to v = gt.

2. Height-Time Equation

h = v₀t + (1/2)gt²

Where: h = height/distance, v₀ = initial velocity, g = gravity, t = time

This equation calculates the distance fallen after a given time. If the object starts from rest, it simplifies to h = (1/2)gt².

3. Velocity-Height Equation

v² = v₀² + 2gh

Where: v = final velocity, v₀ = initial velocity, g = gravity, h = height

This equation relates velocity to height without requiring time. It's particularly useful when you know the height but not the time.

Real-World Applications

Free fall calculations are used in countless real-world scenarios:

  • Physics Education: Teaching kinematics, acceleration, and motion under gravity
  • Engineering: Designing safety systems, calculating impact forces, and analyzing drop tests
  • Sports: Analyzing diving, skydiving, and bungee jumping physics
  • Aerospace: Calculating re-entry trajectories and parachute deployment
  • Construction: Analyzing falling objects, safety calculations, and demolition
  • Entertainment: Creating realistic physics in games and simulations
  • Research: Studying gravity, testing equipment, and conducting experiments
  • Safety Engineering: Calculating fall distances and impact velocities for safety systems

Units and Measurements

Free fall calculations use various units depending on the application:

  • Velocity: m/s (SI), ft/s (US), km/h, mph
  • Time: seconds (s), milliseconds (ms), minutes (min)
  • Height/Distance: meters (m), feet (ft), kilometers (km), miles (mi)
  • Gravity: m/s² (SI), ft/s² (US), or g (standard gravity = 9.80665 m/s²)

Standard Values:

  • Earth's gravity: g = 9.80665 m/s² = 32.174 ft/s²
  • Moon's gravity: g = 1.62 m/s² (about 1/6 of Earth's)
  • Mars's gravity: g = 3.71 m/s² (about 38% of Earth's)

Common Free Fall Calculations

Example 1: Object Dropped from Rest

An object is dropped from a height of 100 meters. What is its velocity when it hits the ground? (g = 9.80665 m/s²)

v₀ = 0 m/s, h = 100 m, g = 9.80665 m/s²

v² = v₀² + 2gh = 0² + 2 × 9.80665 × 100 = 1961.33

v = √1961.33 = 44.29 m/s

Example 2: Time to Fall

How long does it take for an object to fall 50 meters from rest? (g = 9.80665 m/s²)

v₀ = 0 m/s, h = 50 m, g = 9.80665 m/s²

h = (1/2)gt²

50 = 0.5 × 9.80665 × t²

t² = 10.194, t = 3.193 s

Example 3: Height After Time

How far does an object fall in 3 seconds from rest? (g = 9.80665 m/s²)

v₀ = 0 m/s, t = 3 s, g = 9.80665 m/s²

h = (1/2)gt² = 0.5 × 9.80665 × 3² = 44.13 m

Example 4: With Initial Velocity

An object is thrown downward with an initial velocity of 10 m/s. What is its velocity after falling 20 meters? (g = 9.80665 m/s²)

v₀ = 10 m/s, h = 20 m, g = 9.80665 m/s²

v² = v₀² + 2gh = 10² + 2 × 9.80665 × 20 = 492.27

v = √492.27 = 22.19 m/s

Free Fall vs. Other Motion

Understanding the difference between free fall and other types of motion is important:

  • Free Fall: Motion under gravity only, no air resistance or other forces
  • Terminal Velocity: When air resistance balances gravity, velocity becomes constant
  • Projectile Motion: Motion with both horizontal and vertical components
  • Constant Velocity: Motion with no acceleration (different from free fall)

Our calculator assumes true free fall (no air resistance). For real-world applications with air resistance, you would need more complex calculations involving terminal velocity.

Gravity Variations

Gravity varies depending on location:

  • Earth's Surface: Approximately 9.80665 m/s² (varies from 9.78 to 9.83 m/s²)
  • Altitude: Gravity decreases slightly with altitude (about 0.003 m/s² per kilometer)
  • Latitude: Gravity is slightly stronger at the poles than at the equator
  • Other Planets: Each planet has its own gravitational acceleration

For most calculations, using the standard value of 9.80665 m/s² is sufficient, but our calculator allows you to input custom gravity values for different scenarios.

Frequently Asked Questions (FAQ)

What is free fall?

Free fall is the motion of an object falling solely under the influence of gravity, with no air resistance or other forces. In free fall, all objects accelerate at the same rate regardless of their mass (in a vacuum).

Do heavier objects fall faster?

No! In true free fall (vacuum), all objects fall at the same rate regardless of mass. This was famously demonstrated by Galileo. In air, heavier objects may appear to fall faster due to air resistance, but in a vacuum, a feather and a hammer fall at the same rate.

What is the acceleration due to gravity?

On Earth's surface, the standard acceleration due to gravity is 9.80665 m/s² (32.174 ft/s²). This value varies slightly with location, altitude, and latitude, but 9.80665 m/s² is the standard value used in most calculations.

Can I use this calculator for objects thrown upward?

Yes! If an object is thrown upward, use a negative initial velocity. The calculator will calculate the motion correctly, including the upward phase and the downward free fall phase.

What about air resistance?

This calculator assumes no air resistance (true free fall). In reality, air resistance affects falling objects, especially at high velocities. For calculations involving air resistance, you would need to account for terminal velocity and use more complex equations.

How do I calculate free fall on other planets?

Simply change the gravity value in the calculator. For example, on the Moon, use g = 1.62 m/s². On Mars, use g = 3.71 m/s². The calculator will work with any gravity value you provide.

Conclusion

Understanding free fall is fundamental to kinematics and has countless practical applications in physics, engineering, and everyday life. Our Free Fall Calculator simplifies these calculations, supporting custom gravity values and multiple unit conversions to make solving free fall problems easy and accurate.

Ready to explore more kinematics concepts? Check out our Velocity Calculator for general velocity calculations, our Acceleration Calculator for acceleration analysis, or our Terminal Velocity Calculator for motion with air resistance.

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