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PocketLab Experiment on Centripetal Acceleration with a 3-speed Ceiling Fan

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Submitted by Rich on Mon, 06/26/2017 - 18:22

There are two approaches that the teacher can take to doing this experiment on centripetal acceleration with a three-speed ceiling fan and PocketLab.

The first choice is for those with an available three-speed ceiling fan.  In this case students can collect all data by actually performing the experiment themselves.  The PocketLab should be mounted to one of the ceiling fan blades with a very strong double stick mounting tape.  For safety, however, students should still wear goggles.  The author mounted PocketLab as close to the center pivot point of the blade as possible.  This was necessary to avoid exceeding the 8g limit for the PocketLab accelerometer at the highest fan speed.

The second choice is simply to use the data captured by the author from files attached to this project.  An empty data table on which students can use the data to make calculations related to the circular motion of the ceiling fan is found in the attached pdf file.  Accelerometer and gyroscope csv files are also attached, allowing students to obtain centripetal acceleration and angular velocity data, respectively.  Alternately, students can use the attached PocketLab movie to obtain this data.

The photo below shows the fan and mounted PocketLab.  An NSTA ruler has been added so that students can determine the radius of the circle in which PocketLab revolves.  From the photo, students should be able to (1) determine whether to use the x, y, or z component of acceleration to measure centripetal acceleration, and (2) determine whether to use the x, y, or z component of angular velocity to measure the angular velocity of the revolving PocketLab.

Paddle Fan With Ruler


The figure below shows the base event timeline used when making the movie.  The fan is first turned on after which it reaches high speed after several seconds.  Then the fan is switched to medium speed, also reached after several seconds.  Then the fan is switched to low speed, reaching this speed after several seconds.  Finally, the fan is turned off, and begins to slow down.  The PocketLab accelerometer and gyroscope csv files will both show shapes similar to the figure below when selecting the appropriate x, y, and z components.

Time Progression Graph


The movie used for all data collection can be seen below.

Time Progression Graph
Grade Level