The Physics Front is a free service provided by the AAPT in partnership with the NSF/NSDL.
Computer Program Detail Page
Ejs Free Fall Cartesian Model
This interactive model displays the dynamics of a ball dropped near the surface of Earth onto a table top. The model was designed to extend the free fall concept to include motion in the horizontal direction, allowing students to explore the impulsive normal force that reverses the ball's velocity upon collision with the table. Initial conditions for the ball are an initial positive velocity in the x direction and zero initial velocity in the y direction. The coefficient of restitution for the ball's collision with the platform is less than one.
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
Editor's Note:The motion of a bouncing ball provides an excellent way to integrate concepts of Law of Conservation of Energy, impulse and momentum, and motion in two dimensions. We recommend introducing this computer modeling activity after students have explored bouncing balls in hands-on activities. SEE RELATED MATERIALS for link to a recommended companion resource.
6-8: 4E/M4. Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves.
9-12: 4E/H9. Many forms of energy can be considered to be either kinetic energy, which is the energy of motion, or potential energy, which depends on the separation between mutually attracting or repelling objects.
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/H4. Whenever one thing exerts a force on another, an equal amount of force is exerted back on it.
11. Common Themes
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.
%0 Computer Program %A Christian, Wolfgang %D June 1, 2008 %T Ejs Free Fall Cartesian Model %7 1.0 %8 June 1, 2008 %U http://www.compadre.org/Repository/document/ServeFile.cfm?ID=7347&DocID=499
Disclaimer: ComPADRE offers citation styles as a guide only. We cannot offer interpretations about citations as this is an automated procedure. Please refer to the style manuals in the Citation Source Information area for clarifications.
This lesson plan from the University of Oregon Virtual Laboratory provides a very structured lab for students to investigate the motion of a bouncing ball, then apply their learning to a simulated situation.