I have long appreciated Paul Hewitt’s “Figuring Physics” in each month’s issue of The Physics Teacher. I often use them for student discussions in my classes. The November 2021 “Figuring Physics” on acrobat energies1 presents a straightforward situation, which can be treated simply, as shown by the solution2 provided in the December 2021 issue, so long as a simplifying assumption is made. Relaxing this assumption provides an opportunity to introduce other important concepts and explore rich behavior, all at a level that is accessible to introductory students.

The original feature poses the following scenario and question:

Acrobat Barry stands atop an elevated platform. He steps off the platform and lands on one end of a teeterboard as shown, which causes Arnie to be propelled into the air—a common routine with circus acrobats. Friction is negligible. Barry weighs twice as much as Arnie. If Barry’s initial height is...

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