Packet 9: Bonus 3
This phenomenon causes a transfer of electric charge in the triboelectric effect. For 10 points each:
[10e] Name this force that opposes an object's movement across a surface. The namesake coefficient of the "static" type of this force is always greater than or equal to the "dynamic" version.
ANSWER: frictional force
[10m] This scientist names a law of dry friction. Another of his laws states that the magnitude of the electrostatic force between two point charges is inversely proportional to the square of the distance between them.
ANSWER: Charles-Augustin de Coulomb [accept Coulomb’s law]
[10h] For an object on an inclined plane, the condition for slipping at constant velocity equates the angle of incline to this function of the coefficient of static friction.
ANSWER: arctangent [or inverse tangent; reject “cotangent”]
<Physics — Kevin Qiu> | SHOW-ME Four Packet 9
| Heard | PPB | E % | M % | H % |
|---|---|---|---|---|
| 26 | 13.85 | 100% | 31% | 8% |
Conversion
| Team | Opponent | Part 1 | Part 2 | Part 3 | Total | Parts |
|---|---|---|---|---|---|---|
| Chelsea | White Cloud A | 10 | 0 | 0 | 10 | E |
| DeWitt A | Hillsdale Academy D | 10 | 0 | 0 | 10 | E |
| Detroit Catholic Central A | Traverse City Central A | 10 | 0 | 0 | 10 | E |
| Detroit Catholic Central C | Okemos A | 10 | 0 | 0 | 10 | E |
| Detroit Country Day A | U of D Jesuit | 10 | 10 | 0 | 20 | EM |
| Grand Ledge | Troy A | 10 | 0 | 0 | 10 | E |
| Hillsdale Academy A | Williamston | 10 | 0 | 0 | 10 | E |
| Hillsdale Academy B | Traverse City Central B | 10 | 0 | 0 | 10 | E |
| Hillsdale Academy C | Taylor | 10 | 0 | 0 | 10 | E |
| New Boston Huron | Holt | 10 | 0 | 0 | 10 | E |
| New Buffalo A | Coldwater | 10 | 0 | 0 | 10 | E |
| Okemos B | Troy B | 10 | 10 | 0 | 20 | EM |
| Rockford A | DeWitt B | 10 | 0 | 0 | 10 | E |
| Rockford B | New Buffalo B | 10 | 0 | 0 | 10 | E |
| Utica Academy | Detroit Catholic Central B | 10 | 10 | 0 | 20 | EM |
| White Cloud B | Detroit Country Day B | 10 | 0 | 0 | 10 | E |
Summary
| Tournament | Edition | Match | Heard | PPB | E % | M % | H % |
|---|---|---|---|---|---|---|---|
| Rube Goldberg XIX | 11/20/2025 | ✓ | 16 | 11.88 | 100% | 19% | 0% |
| SHOW-ME Four Nationwide HS | 11/20/2025 | ✓ | 5 | 20.00 | 100% | 80% | 20% |
| SPOOKY IX | 11/20/2025 | ✓ | 5 | 14.00 | 100% | 20% | 20% |