Free Fall Simulator
Gravitational Acceleration • Kinematics • Terminal Velocity — Simulate • Explore • Practice • Quiz
1 Overview
This free free fall simulator lets you drop virtual objects under gravitational acceleration g = 9.81 m/s² and observe the kinematics equations in action. The interactive canvas displays the falling object with a real-time height vs time graph, while readout cards show height, distance fallen, velocity, time, g value, and planet. You can compare gravity on Earth, Moon, Mars, and Jupiter, toggle air resistance to observe terminal velocity, and drop two balls simultaneously to verify that mass does not affect free fall in a vacuum.
The tool demonstrates the core free fall equations — s = ½gt², v = gt, v² = 2gs, and t = √(2h/g) — with animated visual proof. Designed for physics and engineering students studying kinematics and gravitational mechanics.
2 Getting Started
The simulator opens in Simulate mode on Earth with a default drop height of 20 m. The canvas shows the ball at the top of the drop tower with the ground below. Six readout cards display Height, Distance Fallen, Velocity, Time, g, and Planet.
Use the Mode pills to switch between Simulate, Explore, Practice, and Quiz. The Planet pills switch between Earth, Moon, Mars, Jupiter, and a Custom g option. Toggle checkboxes enable Air Resistance and a Two Balls comparison mode.
3 Simulate Mode
Set the Drop Height (1–100 m) using the slider. Select a planet to set the gravitational acceleration, or use the Custom option to enter any g value (0.5–30 m/s²). Press Drop to release the ball.
The ball accelerates downward and the readout cards update in real time: velocity increases linearly with time (v = gt), and distance grows quadratically (s = ½gt²). The canvas graph plots both distance and velocity versus time.
Air Resistance: Toggle this on to see the ball reach terminal velocity — the speed at which drag force equals weight and acceleration drops to zero. The ball falls more slowly and takes longer to hit the ground.
Two Balls: Enable this to drop two balls of different sizes simultaneously. In vacuum (air resistance off), both hit the ground at the same time, replicating Galileo’s famous experiment. With air resistance on, the larger ball falls slightly faster due to its lower drag-to-weight ratio.
Press Reset to return the ball to the starting position.
4 Explore Mode
Explore mode provides concept cards across four categories: Gravity Basics (what is g, variation with altitude and latitude), Kinematics (the four free fall equations, derivations), Free Fall (Galileo’s experiment, Apollo 15, terminal velocity), and Applications (drop towers, skydiving, parachute design). Each card includes a formula, canvas diagram, and worked numerical example.
Use this mode to understand the theory behind the simulation — why all objects fall at the same rate in vacuum, how air resistance creates terminal velocity, and how the kinematic equations are derived from constant acceleration.
5 Practice & Quiz
Practice mode generates unlimited random problems: calculate fall time from a given height, find the velocity at impact, determine the height from which an object was dropped given its impact speed, or compare fall times on different planets. Full step-by-step solutions are shown for incorrect answers.
Quiz mode presents 5 randomised questions per session, mixing conceptual items (e.g., what happens to a feather and hammer on the Moon) with numerical calculations. A detailed score breakdown is shown at the end.
6 Tips & Best Practices
- Compare planets: Drop from the same height on Earth, Moon, and Jupiter to see how dramatically different g values affect fall time and impact velocity.
- Use Two Balls mode with air resistance off to prove that mass does not affect free fall in a vacuum — both balls hit the ground simultaneously.
- Toggle air resistance to see terminal velocity emerge: the velocity readout flattens as drag equals weight.
- Use Custom g to simulate free fall on any celestial body — try Venus (8.87 m/s²) or Pluto (0.62 m/s²).
- Check the formula row below the readouts to see all four kinematic equations at a glance.
- The simulator works offline once loaded — ideal for classroom demonstrations.
Understanding Free Fall and Gravitational Acceleration
Free fall is one of the most important concepts in classical mechanics. It describes the motion of an object falling solely under the influence of gravity, with no other forces acting on it. In the ideal case (a vacuum), all objects fall at the same rate regardless of their mass or shape. This remarkable insight, attributed to Galileo Galilei, overturned centuries of Aristotelian thinking and laid the foundation for Newtonian mechanics.
The acceleration due to gravity (denoted g) is approximately 9.81 m/s² at Earth's surface. This means a freely falling object increases its speed by 9.81 metres per second every second. This value varies slightly depending on altitude, latitude, and local geological conditions — from about 9.78 m/s² at the equator to 9.83 m/s² at the poles. On other celestial bodies, g differs dramatically: 1.62 m/s² on the Moon, 3.72 m/s² on Mars, and a crushing 24.79 m/s² on Jupiter.
The Kinematic Equations of Free Fall
For an object released from rest at height h, three key equations govern its motion. The distance fallen is given by s = ½gt², showing that displacement increases with the square of time — a parabolic relationship that proves the object is accelerating, not moving at constant speed. The instantaneous velocity at time t is v = gt, a linear relationship. Combining these gives the time-independent equation v² = 2gs, which relates velocity directly to distance fallen without needing to know the elapsed time. To find the total fall time from height h, rearrange the distance equation: t = √(2h/g).
Galileo's Experiment and the Universality of Free Fall
Galileo's famous thought experiment (and later physical experiments with inclined planes) demonstrated that in the absence of air resistance, a feather and a hammer fall at exactly the same rate. This was dramatically confirmed on the Moon during the Apollo 15 mission in 1971, when astronaut David Scott dropped a hammer and a falcon feather simultaneously — both hit the lunar surface at the same instant. This principle is fundamental to Einstein's equivalence principle and forms the basis of general relativity.
Air Resistance and Terminal Velocity
In the real world, air resistance (drag) opposes the motion of falling objects. The drag force increases with velocity until it equals the gravitational force, at which point the object reaches terminal velocity and stops accelerating. A skydiver reaches approximately 55 m/s (200 km/h) in the spread-eagle position, while a peregrine falcon can dive at over 90 m/s. Parachutes exploit this principle by increasing drag area to reduce terminal velocity to a safe landing speed of about 5 m/s.
Who Uses This Simulator?
This free fall simulator is designed for engineering students, physics learners, technical education trainees, and educators who need to visualise gravitational acceleration, practise kinematics calculations, and understand the relationship between distance, velocity, and time during free fall. The multi-planet comparison feature makes it especially useful for aerospace and planetary science courses.
Explore Related Simulators
If you found this free fall simulator helpful, explore our Boyle's Law simulator, Charles's Law simulator, Thermal Expansion simulator, and Thermodynamics Cycles simulator for more hands-on practice.