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JOURNALS // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika // Archive

Vestnik Moskov. Univ. Ser. 1. Mat. Mekh., 2025 Number 2, Pages 16–23 (Mi vmumm4667)

This article is cited in 1 paper

Mathematics

Elliptic billiard with cosine law of refraction on confocal quadrics

M. A. Nikulinab

a Lomonosov Moscow State University, Faculty of Mechanics and Mathematics
b Moscow Center for Fundamental and Applied Mathematics

Abstract: For a billiard in an elliptic domain, we consider several confocal quadrics, which divide this domain into several regions each filled with homogeneous media with various densities. When crossing the quadric separating two media, it is assumed that the trajectory deviates from a straight line according to the modified (cosine) law of refraction. For the system obtained in this way, the constant of motion is obtained.

Key words: billiards in an ellipse, integral of motion, modified law of refraction.

UDC: 517.938+514.7

Received: 20.12.2023

DOI: 10.55959/MSU0579-9368-1-66-2-3


 English version:
Moscow University Mathematics Bulletin, Moscow University Mеchanics Bulletin, 2025, 80:2, 97–105

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© Steklov Math. Inst. of RAS, 2026