Packet 4: Bonus 9
This quantity can be written as the sum of two dyadic products minus a term proportional to the energy density of a field. For 10 points each:
[10h] Name this quantity whose divergence is subtracted by a time derivative term to obtain the Lorentz force density of an electromagnetic field.
ANSWER: Maxwell stress tensor [reject “(electromagnetic) stress–energy tensor”]
[10m] The time derivative of a quantity named for this physicist is subtracted to obtain force density. This physicist’s namesake theorem describes conservation of energy for electromagnetism.
ANSWER: John Henry Poynting
[10e] The Maxwell stress can be interpreted as the electromagnetic density of this classical quantity’s flux. This quantity’s conservation is implied by Newton’s laws of motion.
ANSWER: momentum [or linear momentum]
<Editors, Physics> | M. Playoffs 4 (Editors 4)
| Heard | PPB | E % | M % | H % |
|---|---|---|---|---|
| 24 | 8.75 | 79% | 8% | 0% |
Conversion
| Team | Opponent | Part 1 | Part 2 | Part 3 | Total | Parts |
|---|---|---|---|---|---|---|
| British Columbia | Pittsburgh | 0 | 10 | 10 | 20 | ME |
| Bruin | Penn State | 0 | 0 | 0 | 0 | |
| Chicago A | Toronto A | 0 | 0 | 10 | 10 | E |
| Georgetown | Maryland B | 0 | 0 | 0 | 0 | |
| Georgia Tech B | Georgia Tech A | 0 | 0 | 10 | 10 | E |
| Harvard | UC Berkeley A | 0 | 10 | 10 | 20 | ME |
| Illinois A | MIT | 0 | 0 | 10 | 10 | E |
| Illinois B | Northwestern B | 0 | 0 | 10 | 10 | E |
| Johns Hopkins | Columbia B | 0 | 0 | 10 | 10 | E |
| Maryland A | Columbia A | 0 | 0 | 10 | 10 | E |
| Michigan | Stanford B | 0 | 0 | 10 | 10 | E |
| NYU A | Indiana | 0 | 0 | 10 | 10 | E |
| Purdue | Chicago B | 0 | 0 | 10 | 10 | E |
| Rutgers | NYU B | 0 | 0 | 10 | 10 | E |
| Stanford A | Virginia Tech | 0 | 0 | 10 | 10 | E |
| Swarthmore | North Carolina | 0 | 0 | 10 | 10 | E |
| Texas | Cambridge | 0 | 0 | 10 | 10 | E |
| UC Berkeley B | Northwestern A | 0 | 0 | 10 | 10 | E |
| UCF | Cornell | 0 | 0 | 0 | 0 | |
| UCLA | Toronto B | 0 | 0 | 0 | 0 | |
| Vanderbilt | Georgia Tech C | 0 | 0 | 0 | 0 | |
| Virginia | Ohio State | 0 | 0 | 10 | 10 | E |
| WashU | Minnesota | 0 | 0 | 10 | 10 | E |
| Waterloo | Brown | 0 | 0 | 10 | 10 | E |
Summary
| Tournament | Edition | Match | Heard | PPB | E % | M % | H % |
|---|---|---|---|---|---|---|---|
| Main Site | 2026-04-17 | ✓ | 24 | 8.75 | 79% | 8% | 0% |