USAAAO 2024, I кръг — Задача 13

USAAAO 2024 - First Round · 10 февруари 2024 г.

Problem writers

Wesley Andrade, Abhay Bestrapalli, Austin Chen, Justin Chen, Ved Gund, Hagan Hensley, Sandesh Kalantre, Evan Kim, David Lee, Joe McCarty, Arjun Patel, Sahil Pontula, Tara Rezaei, Raul Teixeira, Leo Yao, David Zhang

Условие

Samvit observes a binary star system of masses M1M_1 and M2M_2. Unfortunately, the star with mass M2M_2 is too dim for him to observe it, leading to the following snapshot below.

Coordinate axes with arrows in both directions and an ellipse centred at the origin crossing the axes at (-a,0), (a,0), (0,b) and (0,-b); a grey dot labelled M1 sits at the top of the ellipse at (0,b).

What could Samvit hypothesize to be the position and mass of the other star at this instant that would be consistent with the laws of physics and the orbit snapshot that he sees? To be clear, he has no knowledge of the value of M2M_2 or the period of the binary system.

(a) At (a2−b2,0)(\sqrt{a^2 - b^2}, 0) with mass M1+M2M_1 + M_2

(b) At (0,−b)(0, -b) with mass M1M_1

(c) At (a2−b2,0)(\sqrt{a^2 - b^2}, 0) with mass M1M2M1+M2\frac{M_1 M_2}{M_1 + M_2}

(d) At (−2a2−b2,−b)(-2\sqrt{a^2 - b^2}, -b) with mass M1M_1

(e) At (M2M1a2−b2,0)(\frac{M_2}{M_1}\sqrt{a^2 - b^2}, 0) with mass M2M_2

Отговори

Решение


Оригинал в Архива: usaaao_first_exam_2024-3.pdf · официални решения: usaaao_first_exam_2024_solutions-1.pdf