# Interactive Physics

### Purpose:

In this project, you will identify and analyze a real-world motion scenario which illustrates some physics principles; you will utilize the Interactive Physics program to model the motion in a realistic manner; you will then explore a what if? question by modifying one of the variables in the simulation to explore the effect which it has upon the system.

### Directions:

1. Interactive Physics is a computer program which models the motion of an object under any given conditions. For example, the user can give a car an initial velocity and deceleration rate along a horizontal surface with a given coefficient of friction. The program will simulate the motion of the car until it is brought to a rest. In this lab, you will use Interactive Physics to model the motion of a real-world object. Brainstorm a variety of other motion scenarios which would be suitable for modeling in Interactive Physics. On a separate sheet of paper, accumulate a list of potential scenarios. Select one scenario which you would like to study for this project. The scenario should be interesting (to you), realistic, and simplistic enough to model.

2. Develop the scenario which you have chosen by identifying some realistic values for important motion parameters (mass, length, width, initial speed and direction, etc.). Be as specific and complete as you can; later, you will have to enter these values into the program before running a meaningful simulation. Refer to the table below (Interactive Physics Input Parameters). Develop a list of numerical values for the various input parameters. Identify any physical quantities which you will measure (speed, acceleration, time, position, tension in strings, etc.) in order to evaluate the realistic nature of the motion.

3. Identify a what-if question which you would like to explore. Sample what-if questions for the scenario mentioned above (the car skidding to a stop) include

• what if the car were more massive?
• what if the coefficient of friction was changed?
• what if the initial velocity were different?

Indicate which variable you will modify in the exploration of the what if? question. Identify the dependent variable which you will monitor in order to determine the effect which the independent variable has upon the motion.

4. Describe the purpose of your project. In a few sentences, describe the scenario which you are trying to model and identify the what if question which you will be exploring. The statement should be a purpose statement (procedural steps such as " we will change the mass and measure the new stopping distance" should not be included in a purpose).

5. Describe the model which you will construct using Interactive Physics - this includes:

• a diagram of what the simulation set-up will look like (showing objects, input boxes, measuring tools, etc.); this may require that you look at the program for approximately 15 minutes.
• a complete listing of input values for the various objects included in the model (see the table titled Interactive Physics Input Parameters)
• a clearly-stated description of the what if? question which you will explore; a paragraph describing how you will explore the what-if question (what you will change and what you will be looking for); the dependent and independent variables must be clearly stated; specific values for the independent variable should be suggested.

6. Submit a word-processed proposal for your project. The proposal should include a purpose statement (step 4) and a description of the model (step 5). The proposal must be ambitious, clearly-worded and self-explanatory in order to be accepted.

7. Develop a theoretical background for the scenario which you are modeling. Exhaustively describe the physics of the situation. Include diagrams, graphs, and other visuals which have been discussed in class or which you found in the book or other literature. In other words, apply physics to the situation by intelligently discussing the physics principles which apply to the motion scenario which you have selected.

8. Construct a model of the scenario using Interactive Physics; place objects on the screen and assign to them realistic input values. Modify the input parameters until you obtain a realistic model of the motion. Explore the what if? question which you have proposed; monitor the effect which one variable has upon another variable by documenting relevant data and observations in an organized lab notebook. If working in groups, more than one notebook should be maintained in the event that a person with the notebook is absent. Save all files either to a disk or to your personal folder on the server.

9. Submit a written lab report which includes the following sections - Purpose (step 4), Description of the Model (step 5), Theoretical Background (step 7), Data Section (which includes an organized listing of input and output data and observations), and Discussion of Results (in which you briefly describe the successful versions of the model which you have constructed and discuss the findings of your what-if question; support your findings with logic and by reference to the collected data.) Make explicit reference to the names of the simulation files which you have saved.

10. Save your simulation files in your teacher's folder in the ToTeach folder on the server. Your teacher will probably have prepared a folder with your name so that you can drop all your files in the appropriate folder. To save the files, open the file in Interactive Physics and select Save As... from the File menu. Find the appropriate ToTeach folder on the server and click OK.

### Interactive Physics Input Parameters

In order to model a motion, Interactive Physics must first know specific information about a variety of physical quantities for various objects (sphere, rectangles, polygons, strings, springs, etc.). The following listing summarizes important input parameters.

 x-position x-velocity (vx) gravity friction coefficient materials y-position y-velocity (vy) air resistance elasticity (important for collisions) length and width

### Due Dates:

The following due dates have been tentatively assigned for the completion of your project.

 Submission of Proposal (step 6) 10/10 Submission of Theoretical Background (step 7) 10/14 Submission of Interactive Physics File on server (step 8 and 10) 10/17 Submission of Final Paper (steps 9 and 10) 10/20