The detailed solution of a problem originally proposed for a college-admission exam is discussed.The problem involves the oscillation of a mass-spring system in an initially accelerated referentialand the determination of the amplitude of vibration after the referential has reached the rest.We show that the value of this amplitude depends essentially on the relation between the timeof acceleration and the period of oscillation. In the limit case when the period of oscillation ismuch longer than the time of acceleration, the system approaches a conservative system and theanswer can be found by applying the principle of conservation of mechanical energy. The presentedproblem constitutes an interesting exercise for the discussion (at either high-school or college level)of subjects like fictitious forces, coordinates change, and non-conservation of mechanical energy innon-inertial reference systems.
