Teaching Physics with the Physics Suite

Edward F. Redish

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The Return of the Skateboarding TA

In this problem, you will use the program Logger ProTM to analyze motion, following on the work you did in problem K21. The instructions for using this program (and where to find it on the Maryland campus) are given in the instructions document. We strongly recommend that you download and print this document for reference while doing this problem.

You will need to download two files to your desktop:

Download these files by right-clicking on them in the bulleted list, selecting "Save link as...", and saving them to your desktop.

a. This time, take data from the movie using Logger ProTM to get a value for the TA's horizontal velocity by curve fitting a graph. How does the the TA's horizontal velocity compare to the horizontal velocity of the ball from last week? Does this make sense?

b. Based on the data table in Logger Pro, what is the frame rate (the number of frames of the movie taken by the camera in 1 sec) of the camera? Explain your answer

For the next part, you need your Logger Pro (.cmbl) file from problem K21. If you do not have your Logger Pro file from problem K21, you must recreate the graphs and fit the y-velocity curve first.

c. From the y-velocity vs time of the ball in problem K21, find the vertical acceleration of the ball. Compare this value to 9.8 m/s2 and find the percent deviation.

d. Could one possible reason that the that acceleration is not exactly 9.8 m/s2 is that Logger Pro is incorrect about the frame rate of the camera? Would Logger Pro think that the frame rate is larger or smaller than the actual frame rate of the camera in order to get your value of the acceleration? Explain. Discuss how you might find the frame rate that would lead you to measure a value of the acceleration equal to 9.8 m/s2.

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Page last modified October 2, 2010: K22