As on all forms, be sure you have your data backed up in another document, and in your lab notebook.

Submitting Assignment: Analysis of Angular Velocity of a Strap

Your course (e.g., Mth 151, Mth 173, Phy 121, Phy 232, etc. ):

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Remember that it is crucial to enter your access code correctly.  As instructed, you need to copy the access code from another document rather than typing it.

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Note that the data program is in a continual state of revision and should be downloaded with every lab.

Most students report spending 1 hour or less on this analysis.  Few students report over 2 hours, but a very small minority report times well in excess of 2 hours (including one report of over five times this long).  If this experiment seems to be taking an excessively long time, submit this form with the analysis you have been able to complete and a good description of the process you are using to perform the analysis.

Using your data for Angular Velocity of a Strap and using whatever features of the Data Program you find appropriate, analyze three different trials of the program in order to determine average velocity vs. midpoint clock time for each of the three trials.

The three trials you should use are as follows:

• The trial with the least average angular velocity.
• The trial with the greatest average angular velocity.
• The trial whose average angular velocity is closest to the mean of the average velocities you observed.

Clarification of the terminology:

• Angular velocity is measured here in degrees per second.  In the experiment you found the average angular velocity for each of about 7 different trials, so you will have about 7 different average angular velocities.
• 'Average angular velocity' means the average angular velocity for a single trial, from the initial instant to the instant at which the strap came to rest.
• 'Clock time' means the time as read on a running clock..  This clock time can be measured from the instant of your first measurement.  Clock times will continue to increase throughout a trial, and this would be so even if the strap was speeding up and the time intervals between click decreasing.  Clock times are not to be confused with time intervals.

For each of the three trials you report here you need to calculate the following:

• The average angular velocity for each 180-degree interval of rotation.
• The midpoint clock time for each 180-degree interval of rotation; this is the clock time halfway between the clock time at the beginning and the clock time at the end of the rotation.  Be very sure you know what 'clock time' means, as opposed to 'time interval'.  A very common error here is to report half the time interval rather than the midpoint clock time.

Report in the first line below the data you previously obtained for the trial with the least average velocity.

Starting in the second line report your average angular velocity vs. midpoint clock time data for this trial.  You will report a clock time and an average angular velocity for each 180-degree interval.  Use comma-delimited format with one interval reported per line. 

After reporting the requested information, explain how you obtained your midpoint clock times and your average angular velocities.

Your answer (start in the next line):

Report in the first line below the data you previously obtained for the trial with the greatest average velocity.

Starting in the second line report your average angular velocity vs. midpoint clock time data for this trial.  You will report a clock time and an average angular velocity for each 180-degree interval.  Use comma-delimited format with one interval reported per line. 

After reporting the requested information, explain how you obtained your midpoint clock times and your average angular velocities.

Your answer (start in the next line):

Your answer (start in the next line):

For each trial construct a graph of average angular velocity vs. midpoint clock time.  Fit the best possible straight line to your data.  You may do this using the computer, but there aren't many data points and a hand-drawn graph can be constructed quickly.  A very reasonable best-fit line can be drawn with the goal of minimizing the total distance of the points from the line.  ( If you choose to use Excel you can construct the best-fit line by right-clicking on a data point and choosing Add Trendline; select a linear trendline and also go under Options and click on the Display Equation option. )

Report in the space below the slope and the vertical-axis intercept of your straight line for each of the three trials you graphed.  Report trial in each of the first three lines. Report the trials in the same order you used above.  Starting in the fourth line describe your three graphs and briefly explain how you determined the slope and vertical-axis intercepts of your lines.

Your answer (start in the next line):

In the space below report for each of your three trials whether the trend of the data was well-fit by a straight line, or whether there appears to be some curvature in the trend of one or more of your graphs.

Your answer (start in the next line):

In the space below discuss whether your data indicates whether the angular acceleration (i.e., the rate of change of angular velocity) was or was not constant for each of your three trials, and the degree to which you believe your data supports the hypothesis that the angular acceleration of a strap on a die is constant.

Your answer (start in the next line):

Your instructor is trying to gauge the typical time spent by students on these experiments.  Please answer the following question as accurately as you can, understanding that your answer will be used only for the stated purpose and has no bearing on your grades: 

• Approximately how long did it take you to complete this experiment?

Your answer (start in the next line):

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