Physics behind inverting Aggie Ring spin

Your Aggie Ring represents 90 hours of academic achievement, but did you know it also illustrates some puzzling physics?

Set yours on a table upside down, spin it — and watch it invert so that it’s suddenly spinning right side up, with the ring crest and shield on top.

Texas A&M University’s Dr. Tatiana Erukhimova, a physics professor who goes viral on social media with her creative physics demonstrations, explained the forces at work.

“When you spin the ring on the heavy end, the force of friction creates a torque that raises the center of mass until the ring overturns and starts spinning on the lighter end,” she said.

The principle is often demonstrated with a toy called a tippe top, which like an Aggie Ring is heavier at one end and flips itself onto the small end while spinning. When these toys became popular in the 1950s, physicists including Niels Bohr were intrigued. Initially, even physicists came up with different explanations for what was happening.

When your Aggie Ring rests on a tabletop, crest down, “the center of mass of the ring sits quite low above the table surface,” Erukhimova said. As the ring spins, friction between the ring and the table creates an additional rotating force (torque). 

This torque “pushes the ring axis down until the ring overturns,” she said. “In contrast, in standard tops, the torque due to friction tends to align the axis of the top with the vertical axis."

Similarly-shaped rings can also duplicate the feat, but the flat crest of an Aggie Ring seems to assist in getting a smooth spin started.

More about the Aggie Ring:

• Learn how to apply for or donate to Aggie Ring Scholarships
• What to do if you find or lose an Aggie Ring
• Why is the Aggie Ring program #1 in the United States?
• Your Aggie Ring has a lifetime repair warranty
• Symbolism of the Aggie Ring design
• Stories of found Aggie Rings returned to owners