Support for Java Applets, including Physlets, has been discontinued by browsers and Oracle. Thus, traditional Java-based Physlets are no longer supported on this website. Please note Open Source Physics (OSP) Java programs continue to run on computers with Java if users download the jar file.

The OSP team is busy updating and developing simulations using HTML5 + JavaScript.
These simulations run on almost all platforms including tablets and cellphones. Explore the Third Edition of Physlets Physics or search OSP for JavaScript to find these simulations.


The second edition to Physlet Physics represents a major change in how the 800 Physlet-based interactive materials are delivered to teachers and students alike. Instead of accessing materials off of the CD that came with the first edition, now users simply access the Physlet Physics 2E Compadre site at This new partnership with ComPADRE also allows us to update materials and therefore provide the best materials to teachers and students. Housing the material on ComPADRE also lowers the barrier for adoption, since anyone can adopt these materials.

In addtion, Physlet Physics 2E:

Copyright and Conditions of Use

Except for the exercises placed in the public domain, Physlet® Physics 2E, i.e., the text and associated script for the Illustrations, Explorations, and Problems in Physlet® Physics 2E are copyrighted by Wolfgang Christian and Mario Belloni for the English language and all other languages. The materials in Physlet Physics 2E are released under the Creative Commons Attribution-NonCommercial-NoDerivs License. More details can be found on the Conditions of Use page or by clicking the Creative Commons link at the bottom of each page in Physlet Physics 2E.

Instructor Resources

In addition to the interactive curricular material on this site, instructors may also wish to view the Physlet Physics Instructor's Guide by Anne J. Cox and Melissa H. Dancy. The Physlet Physics Instructor's Guide are available upon request.


In addition to the lengthy and complete acknowledgements to the First Edition which can be found below in the Preace to the First Edition, there are several people we wish to thank for making the Second Edition possible. We thank Bruce Mason, Lyle Barbato, and Matt Riggsbee of ComPADRE for their tireless work in getting our materials into ComPADRE. We also thank Beth Cunningham, Bob Hilborn, and all of the American Association of Physics Teachers (AAPT) for their continuing support of Physlets and ComPADRE. We thanks our colleagues at Davidson College for their support over the years, especially the Physics Department, Dean of Faculty Clark Ross, and President Carol Quillen. Without Davidson College's support of Mario Belloni's sabbatical, this project could not have happened.

Finally, and most importantly, we again express our sincerest thanks to those who have encouraged us the most: our spouses, Barbara and Nancy, and our children, Beth, Charlie, and Konrad and Emmy.

Preface to the First Edition

By now it is hard to imagine an instructor who has not heard the call to "teach with technology," as it has resounded through educational institutions and government agencies alike over the past several years. However, teaching with technology has often resulted in the use of technology for technology's sake and also often resulted in the development of tools that are not pedagogically sound. For example, consider PowerPoint lectures, which are a popular response to the "teach with technology" push. While PowerPoint lectures are more colorful, they are generally no more interactive than chalkboard lectures. The physics community has, to its credit, worked to use technology in a variety of highly interactive and effective ways including wireless classroom response systems that allow for in-class quizzing of students and MBLs (microcomputer-based laboratories) that free students from the drudgery of data collection so that they can spend more time understanding the underlying physical concepts. Into this we offer Physlet Physics, a collection of ready-to-run interactive computer simulations designed with a sound use of pedagogy in mind. The aim of Physlet Physics is to provide a resource for teaching that enhances student learning and interactive engagement. At the same time, Physlet Physicsis a resource flexible enough to be adapted to a variety of pedagogical strategies and local environments.


Physlet Physics contains a collection of exercises spanning the introductory physics sequence. These exercises use computer animations generated in Java applets to show physics content. We call these Java applets Physlets (Physics content simulated with Java applets). Every chapter of Physlet Physics contains three quite different Physlet-based exercises: Illustrations, Explorations, and Problems.

Illustrations are designed to demonstrate physical concepts. Students need to interact with the Physlet, but the answers to the questions posed in the Illustration are given or are easily determined from interacting with it. Many Illustrations provide examples of physics applications. Other Illustrations are designed to introduce a particular concept or analytical tool. Typical uses of Illustrations would include "reading" assignments prior to class and classroom demonstrations.

Explorations are tutorial in nature. They provide some hints or suggest problem-solving strategies to students in working problems or understanding concepts. Some Explorations ask students to make a prediction and then check their predictions, explaining any differences between predictions and observations. Other Explorations require students to change parameters and observe the effect, asking students to develop, for themselves, certain physics relationships (equations). Typical uses of Explorations would be in group problem-solving and homework or pre-laboratory assignments. Explorations are also often useful as Just-In-Time Teaching exercises. The Worksheets provide students with extra structure to aid in the completion of the Exploration and provide instructors with an easy way to assign Explorations.

Problems are interactive versions of the kind of exercises typically assigned for homework. They require the students to demonstrate their understanding without as much guidance as is given in the Explorations. They vary widely in difficulty, from exercises appropriate for high school physics students to exercises appropriate for calculus-based university physics students. Some Problems ask conceptual questions, while others require detailed calculations. Typical uses for the Problems would be for homework assignments, in-class concept questions, and group problem-solving sessions.

Before You Start

Assigning Physlet Physics material without properly preparing the class can lead to frustration. Although Physlet problems often appear to be simple, they are usually more challenging than traditional problems because novice solution strategies are often ineffective. In addition, small technical problems are bound to occur without testing. We use Physlets extensively in our introductory courses at Davidson College, but we always start the semester with a short laboratory whose sole purpose is to solve a Physlet problem in the way a physicist solves a problem; that is, to consider the problem conceptually, to decide what method is required and what data to collect, and finally to solve the problem. As a follow-up, we then assign a simple Physlet-based exercise that must be completed in one of the College's public computer clusters. This minimal preparation allows us to identify potential problems before Physlet-based material is assigned on a regular basis.

In response to these possible difficulties, we have written Chapter 1: Introduction to Physlets. This chapter provides students and instructors with a guided tutorial through the basic functionality of Physlets. After completing the exercises in Chapter 1, students and instructors alike should be in a position to complete the exercises in the rest of the book.

Before you begin, or assign material to students, you should also read the page on System Requirements.


There are a great many people and institutions that have contributed to our efforts, and we take great pleasure in acknowledging their support and their interest.

We thank our colleague Larry Cain for the many hours he spent reading the manuscript and for providing many insightful comments and suggestions. We also thank our colleagues and our students at Davidson College for testing of Physlet-based material in the classroom and the laboratory. Mur Muchane and the Davidson ITS staff have provided excellent technical support. We would also like to thank the Davidson College Faculty Study and Research Committee and Dean Clark Ross for providing seed grants for the development of Physlet-based curricular material. We also thank Nancy Maydole and Beverly Winecoff for guiding us through the grant application process.

The Physlets project has benefited tremendously from collaborations with non-U.S. universities. In particular, special thanks and recognition go to Francisco Esquembre and Ernesto Martin at the University of Murcia (Spain), to Sasa Divjak at the Universtiy of Ljubljana (Slovenia), and to Frank Schweickert at the University of Kaiserslautern (Germany) for translating Physlet-based material into their respective languages and for maintaining non-English-language Physlets websites.

W.C. would like to thank the numerous students who have worked with him over the years developing programs for use in undergraduate physics education. Some of our best Physlets are the result of collaborative efforts with student coworkers. In particular, we would like to single out Mike Lee, Cabel Fisher, and Jim Nolen.

M.B. would like to thank Mario Capitolo, Anne J. Cox, Edward Deveney, Harry Ellis, Kurt Haller, Bill Junkin, Ken Krebs, and Steve Weppner for many useful and stimulating discussions regarding teaching and the incorporation of Physlets with existing curricular material.

Some people have been such frequent contributors of time and ideas that we have brought them in as contributing authors of this book. We would like to thank Anne J. Cox, Melissa Dancy, and Aaron Titus (whose work was supported in part by NSF DUE-9952323), both for their writing and for the many valuable ideas we have gained during our associations with each of them. In addition we would like to thank Thomas M. Colbert for his work creating Worksheets for the Explorations.

Special thanks to Chuck Bennett, Scott Bonham, Morten Brydensholt, Anne J. Cox, Melissa H. Dancy, Dwain Damian, Andrew Duffy, Fu-Kwun Hwang, William Junkin, Steve Mellema, Chuck Niederriter, Evelyn Patterson, Peter Sheldon, Aaron Titus, and Toon Van Hoecke for their contributions of curricular material. In addition we thank Harry Broeders, the CoLoS consortium, Fu-Kwun Hwang, Ernesto Martin, Toon Van Hoecke, and Vojko Valencic for the use of their applets.

We would like to thank all those who reviewed material. During the initial writing we received feedback from Rhett Allain (Southeastern Louisiana University), Cornelius Bennhold (George Washington University), Thomas M. Colbert (Augusta State University), Edward F. Deveney (Bridgewater State College), Kevin M. Lee (University of Nebraska), Chuck Niederriter (Gustavus Adolphus College), and Steve Mellema (Gustavus Adolphus College). We also would like to thank Harry Ellis, Eduardo Fernandez, and Steve Weppner of Eckerd College for the feedback we received from their class testing of the exercises.

Ranking tasks in this book are inspired by the ranking tasks in Ranking Task Exercises in Physics, T. O' Kuma, D. Maloney, and C. Hieggelke. Their Two-Year College (TYC) Workshops have been an especially fruitful arena for the give-and-take of ideas with fellow faculty. The Physlet strategy could not have grown and matured without these opportunities and the exchange of ideas that they afforded.

Both of us express our thanks to Eric Fahlgren, Christian Botting, Mark Pfaktzgraff, and their coworkers at Prentice Hall for supporting the development of Physlets Physics and for all of their hard work getting this book to press on an accelerated schedule. In addition, we thank Ruth Saavedra for her copyediting of the manuscript and Michael Drew and his coworkers at nSight for their work formatting and typesetting this book.

We also wish to express our sincerest thanks to those who have encouraged us the most: our spouses, Barbara and Nancy, and our children, Beth, Charlie, and Konrad and Emmy.

This work was partially supported by the National Science Foundation under contracts DUE-9752365 and DUE-0126439.

The OSP Network:
Open Source Physics - Tracker - EJS Modeling
Physlet Physics
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