What is a hula hoop doing as it circles the center of the body? What’s the physics behind the fun? And how can that inform record-setting hula hoopers like Marawa Ibrahim when they practice spinning 200 hula hoops at once?
Ibrahim holds 12 Guinness World Records, and in this Wired video, Robbie Gonzalez dives into the science and athleticism it takes to accomplish the one she set in 2015: Most hula hoops spun simultaneously. From Wired:
A quick primer on the physics of this stuff: For a Hula-Hoop to continue spinning, one must apply force to the hoop in both the fore-aft and up-down directions. “The Hula-Hoop stays aloft thanks to conservation of angular momentum, but the system is extremely unstable—one little hiccup, and the hoop comes tumbling down,” says Ramesh Balasubramaniam, a sensorimotor neuroscientist at UC Merced and an expert in how the brain and body work together to perform skilled tasks.
In a 2004 study titled “Coordination Modes in the Multisegmental Dynamics of Hula-Hooping,” Balasubramaniam showed that most Hula-Hoopers apply the necessary forces through the coordination of two lower-limb “systems”: The hips and ankles apply force in the fore-aft direction, while the knees add force in the up-down direction. When things are going smoothly, the hip-ankle system and the knee system oscillate in unison. But if you interrupt your hooper’s flow and cause them to falter—say, by redirecting their attention from hooping to counting backwards from 100 in increments of seven—their knees will fall out of phase with the hips and ankles by pumping a little faster to try to restore order to the system.
Read more about why it’s almost impossible to spin 300 hula hoops at once: One Woman Pushes Hula-Hooping to Its Absurd, Glittery Limits.
Then watch these related videos about spinning:
• Angular momentum demo with a Hoberman Sphere
• A circular motion demo with a sparkler and a hula hoop
• The Tea Twister – The science behind Teh Tarik (pulled tea)
• What does it look like to be a hula hoop?
• How A Children’s Toy Led To An Essential Medical Device