Packet 5: Bonus 14
The modern theory of these systems was developed by Walter Elsasser, who introduced a dimensionless number representing the ratio of magnetic forces to the Coriolis force. For 10 points each:
[10m] The Babcock–Leighton model concerns what systems, which share their name with a type of generator that uses rotating magnets with a commutator to create direct current?
ANSWER: dynamos [accept geodynamo or solar dynamo]
[10e] Elsasser’s dynamo theory was the first to use a coordinate system based on this shape, which uses the poloidal coordinate. Plasmas are confined in this shape in a tokamak.
ANSWER: torus [or toroid; accept poloidal-toroidal coordinates]
[10h] Elsasser also names a dimensionless number that quantifies the rate of this process in plasmas, where the motion of lighter electrons creates an electric field that “drags” the heavier ions with them.
ANSWER: ambipolar diffusion [prompt on diffusion]
<FW, Physics> | NAFTA-Packet-5
| Heard | PPB | E % | M % | H % |
|---|---|---|---|---|
| 43 | 14.88 | 88% | 61% | 0% |
Conversion
| Team | Opponent | Part 1 | Part 2 | Part 3 | Total | Parts |
|---|---|---|---|---|---|---|
| Lex | [Redacted] | 0 | 10 | 0 | 10 | E |
| The Worst Trade Deal in the History of Trade Deals | W&L+Friend | 0 | 10 | 0 | 10 | E |
| WashU | Maybe Ever | 10 | 10 | 0 | 20 | ME |
| four high school generalists shock natives with fluent stock in Tocharian B | St. Marx | 0 | 10 | 0 | 10 | E |
Summary
| Tournament | Edition | Match | Heard | PPB | E % | M % | H % |
|---|---|---|---|---|---|---|---|
| 2026 NAFTA at Stanford | 01/17/2026 | ✓ | 4 | 17.50 | 100% | 75% | 0% |
| 2026 NAFTA at UBC | 01/17/2026 | ✓ | 2 | 5.00 | 50% | 0% | 0% |
| 2025 NAFTA Online | 02/14/2026 | ✓ | 4 | 12.50 | 100% | 25% | 0% |
| 2026 NAFTA at Vanderbilt | 02/14/2026 | ✓ | 3 | 16.67 | 100% | 67% | 0% |
| 2025 NAFTA at Toronto | 09/13/2025 | ✓ | 5 | 16.00 | 100% | 60% | 0% |
| 2025 NAFTA at Maryland | 09/27/2025 | ✓ | 5 | 12.00 | 60% | 60% | 0% |
| 2025 NAFTA at Harvard | 10/04/2025 | ✓ | 3 | 20.00 | 100% | 100% | 0% |
| 2025 NAFTA at Oxford | 10/11/2025 | ✓ | 4 | 20.00 | 100% | 100% | 0% |
| 2025 NAFTA at Chicago | 11/08/2025 | ✓ | 6 | 16.67 | 100% | 67% | 0% |
| 2025 NAFTA at Columbia | 11/08/2025 | ✓ | 5 | 12.00 | 80% | 40% | 0% |
| 2025 NAFTA at Richmond | 12/20/2025 | ✓ | 2 | 10.00 | 50% | 50% | 0% |