These entities are the input to an inverse problem solved by Binet’s equation. Using Delaunay variables to parametrize these entities, one can show the conservation of Tisserand’s parameter. The shape of these entities may be described by the Laplace–Runge–Lenz vector. Bertrand’s theorem states that these entities are only necessarily closed for two power-law potentials. The vis-viva equation describes bodies moving along these entities, which are classified as hyperbolic when the dimensionless parameter epsilon is greater than one. An object’s period is proportional to the three-halves power of these entities’ semimajor axis by Kepler’s third law. For 10 points, name these trajectories of objects experiencing an attractive central force. ■END■
| 2025 ACF Nationals | 2025-08-09 | Y | 14 | 93% | 0% | 14% | 65.15 |
| North | Main | Y | 10 | 100% | 0% | 0% | 81.80 |
| Overflow | Main | Y | 3 | 100% | 0% | 33% | 85.67 |
| Pacific Northwest | Main | Y | 10 | 100% | 0% | 30% | 68.10 |
| Florida | Main | Y | 13 | 92% | 0% | 8% | 74.00 |
| Upper Mid-Atlantic | Main | Y | 8 | 100% | 0% | 0% | 63.75 |
| Upstate NY | Main | Y | 8 | 100% | 0% | 0% | 70.63 |
| Southeast | Main | Y | 11 | 100% | 0% | 0% | 70.73 |
| Player | Team | Opponent | Buzz Position | Value |
|---|---|---|---|---|
| Akshansh Chauhan | UTD A | Iowa | 24 | 10 |
| Matthew He | Texas A | Arizona State A | 27 | 10 |
| Yrwin Batan | MIT A | Amherst A | 35 | 10 |
| Ben Richards | Sheffield B | City St George's A | 35 | 10 |
| Will McCurley | Auburn A | Bruin A | 37 | 10 |
| Benjamin Chapman | Toronto A | Toronto B | 38 | 10 |
| David Bass | Johns Hopkins A | Maryland A | 38 | 10 |
| Alex Akridge | Indiana A | UIC | 38 | 10 |
| Shardul Parthasarathy | Illinois A | Louisville B | 39 | 10 |
| Ezra Santos | Chicago A | Notre Dame D | 39 | 10 |
| Philip Yao | Brown A | Harvard | 39 | 10 |
| Alec Riso | Cornell-UG | Dartmouth | 39 | 10 |
| Matthew Sumanen | Georgia Tech A | Georgia Tech C | 39 | 10 |
| Gus Redding | Imperial B | Bristol B | 39 | 10 |
| Kevin Flanagan | Bristol A | Warwick B | 39 | 10 |
| Asha Basu | McGill A | Guelph A | 40 | 10 |
| Braxton Davis | Missouri A | SIUE | 41 | 10 |
| S. A. Shenoy | Georgia Tech B | Vanderbilt B | 41 | 10 |
| Rohit Chintala | Maryland C | George Washington B | 42 | 10 |
| Collin Leck | UCO | Northwestern B | 44 | 10 |
| Sharath Narayan | Northwestern A | Alberta B | 44 | 10 |
| Jacob Finley | Notre Dame A | Chicago D | 45 | 10 |
| Will Zhang | Tufts A | Tufts B | 53 | 10 |
| Sidarth Erat | MIT B | BU | 55 | 10 |
| Mia Clark-Webb | Oxford B | Durham A | 55 | 10 |
| Kai Madgwick | Manchester A | Oxford A | 56 | 10 |
| Agnijo Banerjee | Cambridge A | Edinburgh B | 57 | 10 |
| Oscar O'Flanagan | Imperial A | Birmingham A | 59 | 10 |
| Ethen Sun | Toronto D | Ottawa | 61 | 10 |
| Fern Fang | VCU A | George Mason B | 62 | 10 |
| Mats Miller | Chicago B | Michigan C | 62 | -5 |
| Anirudh Terdal | LSE B | Manchester B | 62 | 10 |
| Raymond Jiang | Illinois C | Louisville A | 66 | 10 |
| Kevin Le | Carleton | Toronto H | 67 | 10 |
| James Xiao | Toronto E | Western Ontario | 67 | 10 |
| Aryan Desarapu | Michigan B | Indiana B | 67 | 10 |
| Matthew Kohn | Williams | Yale A | 67 | 10 |
| Oliver West | Cambridge C | Lancaster A | 67 | 10 |
| Brendan Bridle | Queen's A | McMaster C | 70 | 10 |
| Samir Sarma | Georgia Tech D | Vanderbilt A | 70 | 10 |
| Denali Tran-Le | McGill B | Toronto K | 71 | 10 |
| James Windle | Purdue C | Notre Dame B | 71 | -5 |
| Yashwanth Bajji | Michigan A | Purdue B | 72 | -5 |
| Caleb West | Kentucky | Michigan D | 76 | 10 |
| Joel Dicker | Southampton A | Sheffield C | 76 | -5 |
| Abdelrahman Elsisi | Sheffield A | Warwick A | 79 | 10 |
| Felix Garrett Johnston | Huntsville A | Auburn B | 81 | 10 |
| Camden Walker | WashU B | Truman State | 85 | -5 |
| Max Kolda | Notre Dame E | NYU B | 87 | 10 |
| Shreyas Sinha | Texas B | McGill D | 89 | 10 |
| Jakub Hel | UAB A | Mississippi State A | 89 | 10 |
| Oliver Rothnie | Durham B | Imperial C | 90 | -5 |
| Franklin Wu | Toronto C | McMaster A | 92 | 10 |
| Platon Gorokhov | Toronto F | Toronto G | 92 | 10 |
| Vincent Zhang | Penn A | George Mason A | 92 | 10 |
| Leonard Castine | Penn B | Georgetown A | 92 | 10 |
| Sarah Khan | Queen's B | McMaster B | 94 | 10 |
| Zaire Gibbons | Toronto J | Toronto Metropolitan | 94 | 10 |
| Lesley Kwarteng | Johns Hopkins C | UMBC A | 94 | 10 |
| Eames Weeks | Brown B | Brandeis Lloyd George | 94 | 10 |
| Young Fenimore Lee | Ohio | Arizona State B | 94 | 10 |
| Jeremy Mau | Northwestern C | Rose State | 94 | 10 |
| Nolan Travers | Tulsa | UTD B | 94 | 10 |
| Henry Jameson | LSE A | Edinburgh A | 94 | 10 |
| Gavin Ge | Waterloo | Guelph B | 95 | -5 |
| Misty Chen | Purdue B | Michigan A | 97 | 10 |
| Adil Soubki | Cambridge D | Southampton B | 97 | 10 |
| Christopher Dech | Brandeis Wilson | Brandeis Orlando | 98 | 10 |
| Sam Kemeny | Brandeis Clemenceau | Brown C | 99 | 10 |
| Andres Cordoba | Yale B | BC A | 99 | 10 |
| Ian Parsons | Maryland D | Johns Hopkins B | 100 | 10 |
| Graham Lucas | Bowdoin B | BC B | 100 | 10 |
| Davin Sivertson | Alabama B | Alabama A | 100 | 10 |
| Luke Sloan | McGill C | Toronto I | 102 | 10 |
| Gabriel Avrahami | Georgetown B | Maryland B | 103 | 10 |
| Phillip Jordan | Imperial C | Durham B | 103 | 0 |
| Matthew Wozniak | Michigan C | Chicago B | 106 | 10 |
| Stephen Pace | Guelph B | Waterloo | 108 | 0 |
| Dillon George | Catholic University | George Washington A | 108 | 10 |
| Donal Ryan | Truman State | WashU B | 108 | 10 |
| Sophie Lyman | WashU D | William Woods | 108 | 10 |
| Adrian Dooley | Notre Dame B | Purdue C | 108 | 10 |
| Ethan Burks | Huntsville B | Sewanee A | 108 | 10 |
| Alex Irvine | Sheffield C | Southampton A | 108 | 10 |