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Computer Program Detail Page

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Free Fall Air Resistance Model
written by Andrew Duffy
This simulation allows students to compare the motion of free falling objects with and without the influence of air resistance. Air resistance is the result of collisions of the object's leading surface with air molecules. On Earth, objects falling through the air usually encounter some sort of air resistance, though the amount is dependent upon several factors. In this model, a blue ball falls under the influence of gravity alone. A falling red ball is subject to both gravity and air resistance. The user can adjust the amount of air resistance with a slider. When the simulation is played, graphs are simultaneously plotted that show position vs. time, velocity vs. time, and acceleration vs. time for both falling balls.

See Annotations Below for an editor-recommended, interactive tutorial that further explains free fall and air resistance.

This item was created with Easy Java Simulations (EJS), a modeling tool that allows users without formal programming experience to generate computer models and simulations. To run the simulation, simply click the Java Archive file below. To modify or customize the model, See Related Materials for detailed instructions on installing and running the EJS Modeling and Authoring Tool.

Please note that this resource requires at least version 1.5 of Java (JRE).
1 source code document is available
Subjects Levels Resource Types
Classical Mechanics
- Applications of Newton's Laws
- Motion in One Dimension
= Acceleration
= Gravitational Acceleration
= Position & Displacement
= Velocity
Fluid Mechanics
- Dynamics of Fluids
- High School
- Lower Undergraduate
- Middle School
- Instructional Material
= Interactive Simulation
Appropriate Courses Categories Ratings
- Physical Science
- Physics First
- Conceptual Physics
- Algebra-based Physics
- AP Physics
- Activity
- New teachers
  • Currently 5.0/5

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Intended Users:
Access Rights:
Free access
This material is released under a GNU General Public License Version 3 license.
Rights Holder:
Andrew Duffy, Boston University
Easy Java Simulation, Ejs, acceleration, air resistance, free fall, friction, gravity, position, velocity
Record Cloner:
Metadata instance created April 27, 2010 by Mario Belloni
Record Updated:
March 8, 2016 by wee lookang
Last Update
when Cataloged:
April 16, 2010
Other Collections:


Author: Léo Macena
Posted: June 21, 2016 at 1:04PM
Source: The Open Source Physics collection

Hello Mr. Duffy . I am a college student of Physics in Brazil and I've admired so much your work, in particular , your applet Free Fall Model. I've made ??some big changes in this applet and want to publish it , and I will quote it. May I?
Sorry my poor english, I'm studying recently this language.
Good bye, Mr Duffy.

Léo Macena.

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AAAS Benchmark Alignments (2008 Version)

4. The Physical Setting

4F. Motion
  • 6-8: 4F/M3a. An unbalanced force acting on an object changes its speed or direction of motion, or both.
  • 9-12: 4F/H1. The change in motion (direction or speed) of an object is proportional to the applied force and inversely proportional to the mass.
  • 9-12: 4F/H7. In most familiar situations, frictional forces complicate the description of motion, although the basic principles still apply.
4G. Forces of Nature
  • 3-5: 4G/E1. The earth's gravity pulls any object on or near the earth toward it without touching it.

9. The Mathematical World

9B. Symbolic Relationships
  • 6-8: 9B/M3. Graphs can show a variety of possible relationships between two variables. As one variable increases uniformly, the other may do one of the following: increase or decrease steadily, increase or decrease faster and faster, get closer and closer to some limiting value, reach some intermediate maximum or minimum, alternately increase and decrease, increase or decrease in steps, or do something different from any of these.
  • 9-12: 9B/H4. Tables, graphs, and symbols are alternative ways of representing data and relationships that can be translated from one to another.

11. Common Themes

11B. Models
  • 6-8: 11B/M1. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.
  • 6-8: 11B/M2. Mathematical models can be displayed on a computer and then modified to see what happens.
  • 6-8: 11B/M4. Simulations are often useful in modeling events and processes.

Common Core State Standards for Mathematics Alignments

High School — Functions (9-12)

Interpreting Functions (9-12)
  • F-IF.4 For a function that models a relationship between two quantities, interpret key features of graphs and tables in terms of the quantities, and sketch graphs showing key features given a verbal description of the relationship.?
Linear, Quadratic, and Exponential Models? (9-12)
  • F-LE.1.b Recognize situations in which one quantity changes at a constant rate per unit interval relative to another.
  • F-LE.5 Interpret the parameters in a linear or exponential function in terms of a context.
The Physics Classroom: Free Fall and Air Resistance (Editor: Caroline Hall)
Date: 06/14/2010

This editor-recommended interactive tutorial from The Physics Classroom will help students understand the factors that cause air resistance and how this impacts the motion of free fall. The tutorial engages students with animations, free-body diagrams of an elephant and a mouse in free-fall, and a glimpse of terminal velocity. Students will also do simple calculations.

The Physics Classroom: Free Fall and Air Resistance (html)

This resource is part of a Physics Front Topical Unit.

Topic: Kinematics: The Physics of Motion
Unit Title: Motion in One Dimension

How does air resistance affect the motion of a free-falling object? In this model, a blue ball falls under the influence of gravity alone. The red ball is subject to both gravity and air resistance. Adjust the amount of air resistance with a slider, then watch the changes in the motion graphs.

Link to Unit:
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Record Link
AIP Format
A. Duffy, Computer Program FREE FALL AIR RESISTANCE MODEL (2010), WWW Document, (
A. Duffy, Computer Program FREE FALL AIR RESISTANCE MODEL (2010), <>.
APA Format
Duffy, A. (2010). Free Fall Air Resistance Model [Computer software]. Retrieved July 29, 2016, from
Chicago Format
Duffy, Andrew. "Free Fall Air Resistance Model." (accessed 29 July 2016).
MLA Format
Duffy, Andrew. Free Fall Air Resistance Model. Computer software. 2010. Java (JRE) 1.5. 29 July 2016 <>.
BibTeX Export Format
@misc{ Author = "Andrew Duffy", Title = {Free Fall Air Resistance Model}, Month = {April}, Year = {2010} }
Refer Export Format

%A Andrew Duffy
%T Free Fall Air Resistance Model
%D April 16, 2010
%O application/java

EndNote Export Format

%0 Computer Program
%A Duffy, Andrew
%D April 16, 2010
%T Free Fall Air Resistance Model
%8 April 16, 2010

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Free Fall Air Resistance Model:

Simulates Physics Classroom: Free Fall and Air Resistance

An editor-recommended interactive tutorial that explores the influence of air resistance on free-falling objects and introduces the concept of terminal velocity.

relation by Caroline Hall
Is Based On Easy Java Simulations Modeling and Authoring Tool

The Easy Java Simulations Modeling and Authoring Tool is needed to explore the computational model used in the Free Fall Air Resistance Model.

relation by Mario Belloni
Covers the Same Topic As

This editor-recommended interactive tutorial provides content support on factors causing air resistance and how this affects the motion of free fall.

relation by Caroline Hall

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