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Fathom (complete, 8 minutes) The Pendulum Enter Data Make a Graph Calculate Columns Add a Line Add a Curve What We Overlooked Apply a Correction Use Residuals Logger Pro (complete, 8 minutes) The Pendulum Enter Data Make a Graph Calculate Columns Add a Line Add a Curve What We Overlooked Apply a Correction copyright © 2006 eeps media, last updated February 2, 2006 |
Each link at the left opens a movie that will help you learn how to use Fathom or Logger Pro to do data analysis. Each set has one long movie, broken up into brief episodes, each about one minute long, showing some basic skill. To keep them short, we have skipped many important issues. (But they don't work here, because this is not the resource CD, just the read-me stuff.) NotesFirst of all, there are often many ways to accomplish the same task using either piece of software. Experiment! See what others are doing! We only showed you one technique so you could get started. How do you learn more? Try stuff out. And use the online help that comes with each program. The Pendulum. This shows the setup for a simple pendulum experiment. You measure ten swings of a pendulum using a stopwatch, and measure its length with a tape measure or ruler. We'll use data from this experiment throughout these movies. Enter Data. This shows how to make a data table and enter data by hand. Make a Graph. How to make a scatter plot of the data you just entered. Calculate Columns. How to make a new column that's computed from others. In this case, we timed ten periods, so we need a new column to calculate one period. Add a Line. We see how to put a line on the graph. In this case, there's no reason we should expect the data to be linear. But lines are common, so we learn how to make them—and get rid of them. Add a Curve. If you have studied the pendulum, you might know that there's a
theoretical formula for the period T = 2 * pi * sqrt(L/g) ,L is the length of the pendulum and g is the acceleration of gravity.
If you didn't know this already, you might be able to use the data come up with something like it, but that's beyond the scope of this introduction. What We Overlooked. Usually, in a lab, you overlook something, and have to fix it. With Fathom or Logger Pro, you can often fix it in the data analysis. Here, the length we measured is not the right length; this little movie shows the problem. What we did was not bad, however. In fact, measuring to the knot (see the movie) is a good thing: it's an easy, reliable measurement to make. Measuring to the center of mass of the washer/paper clip assembly is not easy to do well. Apply a Correction. Here we show how to correct for the way we measured the length. The key is not to add the "extra" length by hand. Always record the actual measurement, and let the computer do any corrections. Use Residuals (Fathom only). If you use Fathom, you can use a residual plot to get better values for your parameters. |
Be sure to visit the Den of Inquiry site, http://www.denofinquiry.com. About QuickTimeThese are QuickTime movies. If you use a Mac, you already have QuickTime. If you use Windows, you probably have it, but if you don't, you can download it for free from the Apple site. |