### PHYS 251 - Introduction to Computer Techniques in Physics

Spreadsheets, such as MS Excel, represent a relatively quick and accurate means of doing problems in physics. However, they do present some drawbacks. For one, they present some awkwardness in setting up the problem because of their cell orientation. However, with some thought most problems, even differential equations, can be set up fairly rapidly. Spreadsheets allow one to establish input parameters that can be varied with relative ease. Because of their graphing capability, one is able to display results with reasonably high quality graphics. For serious spreadsheet use, one should supplement the graphics with one of the many scientific graphing packages, many of which are design to work directly with a spreadsheet such as Excel.

### Spreadsheet Example - Projectile Motion

As an example of using a spreadsheet for physics computations, let us consider the example of simple projectile motion contained in the following document: Projectile Motion Simulator. (If you need to refresh your knowledge of projectile motion, then consult the following document: Physics Application: Projectile Motion.

In the example spreadsheet on projectile motion, one should note several points.

1. This example document was produced by Excel by simply saving the spreadsheet workbook as an HTML document with Excel doing all the work.
2. In the layout of the spreadsheet, space has been set-aside in the upper cells for explicit identification of the input parameters, which for this problem are the launch velocity and launch angle.
3. Underneath the Input Parameters, cells have been allocated for Computed Quantities, which are important results. These include the time of flight, T, the range, R, and the maximum height, H.
4. The time of flight has been used to establish the time interval in order to calculate the details of the motion rather than using a time step of say 0.1 seconds for example. The time of flight has been divided into 41 intervals giving a time step of 0.360524 seconds. Thus regardless of the launch velocity and launch angle, the time of flight sets the time step. This avoids having to extend the computations to additional rows with the consequent changes necessary to the graphs.
5. Graphs are provided of the path of the motion, the position in x and y as a function of time, and the velocity components as a function of time.

### Internet Resources for Spreadsheet Programs

Physics & Astronomy Department, George Mason University
Maintained by Amin Jazaeri, amin@physics.gmu.edu