I am delighted to have developed some "Figuring Physics" ideas for The Physics Teacher columnist, Paul Hewitt over the years.
If you want a treasure-trove of Hewitt's "Figuring Physics" (a.k.a. "Next-Time Questions"), you're in luck.
Hewitt's Next-Time Questions at Arbor Scientific
We're in the midst of our study of electrostatics. Usually this brings torrents of rain to Northern California. This year's drought seems to be impervious to my machinations.
In any case, this little puzzle came to mind. It was preceded by the developments of Balancing Charges 1 and Balancing Charges 2 PhyzJobs. But I turned the concept into a standalone puzzle.
We begin with two helium-filled balloons that, when oppositely charged, are exactly balanced. They are attached to a massless bar that has a frictionless hinge at its midpoint.
I'll post the answer in the comments next week. It's a fun one to think through. Maybe it will make the cut for next year's round of "Figuring Physics."