96 of 100 walk away. The rest earn it.
Rotation
- 12. Coin on a turntable — A coin rolls without slipping on a spinning disc…
- 14. Rod dropped on a spinning disc — Find common ω and the μ-independent heat fraction.
Fluids
- 21. The draining vortex — Free-surface shape of a rotating draining tank.
- 22. Iceberg with a cavity — An air pocket changes what exactly about flotation?
Electrostatics
- 31. Charge inside a cube corner — Flux through one face when q sits at a corner.
- 33. The image charge that isn't — A grounded sphere and a dipole walk into a problem…
EMI & Circuits
- 41. Jumping ring, quantified — Not “it jumps” — how high, and what sets the limit?
- 44. Infinite ladder, finite answer — Equivalent resistance seen from the corner node.