Hula hoop diameter versus rotation rate

The 8:00 lab settled on measuring the diameter in centimeters and timing five rotations of the hula hoop in seconds. 

Myena with a 137 cm hoop, the green one is 96 cm

This term I had sufficient hoops to cut and splice hoops generating everything from about 72 cm up to 137 cm in diameter. This was the first term to have actual hoops in a variety of diameters.  Cutting and splicing worked far better than expected and far better than the planned approach of taping overlaps and underlaps as was piloted last summer in Kosrae.

Jasmine demonstrates the rotation rate differences


Cutting sections from some hoops...


Allowed splicing into other hoops.


The shortened hoops were closed with Black Gorilla Tape to form shorter hoops. Hoops ranges in size from 72 cm in diameter up to 137 cm in diameter. I was able to hoop the 88 cm hoop, but only two students could put the 72 cm hoop into a stable orbit, Jasmine in the 8:00 section and Joe Scott at 11:00.


Jasmine with a smaller hoop, Myena with a larger hoop. 


Sanjay gathered his own data which initially came out as having no relationship. Along the way I realized that one has to have the hoop rotating in a stable orbit for consistent measurements of the period to be consistent and in line with the diameter. Any hoop can be "thrown" around one's body for a loop or two at a random rotation rate, that does not represent the longer time frame stable rotation rate. 

8:00 data with my own corrections for the 88 and 96 cm hoops. Time is for five rotations.

Some of the variation in hoop diameters available this term

Tommy measures a hoop diameter

Sean records data with Tommy, Ann Loverina, and Joe Scott


Joe Scott would gather consistent data for his group.



Most students would not try to hoop - something that has not been the case in the past. Prior classes have had students who had hooped at some point in their youth. In section no student had hooping experience. The other group appeared to gather less consistent data as no one could sustain a stable orbit. 

An attempt to build a double length hoop failed. The 137 cm hoop was also too large to store on the shelf that has been used for hoops. A larger hoop could undoubtedly be made, but stiffness is already a problem at 137 cm diameter and storage would be even more problematic. 

Hoops were cut using a saw and knife on a pocket took kit. Ideally there would be joiner pipes at the joints. 

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