2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/94293We consider the vacuum fluctuations contribution to the mass of a mirror in an exactly soluble partially reflecting moving mirror model. Partial reflectivity is accounted for by a repulsive delta-type potential localized along the mirror trajectory. The mirror's mass is explicitly found as an integral functional of the mirror's past trajectory.11 pages, LaTexQuantum Physicstext