An elevator descends at constant speed v. There is a spring suspended from the elevator's ceiling, and a particle is hanging off it. It is at rest relative to the elevator. Suddenly the elevator stops. At what magnitude does the spring oscillate? IS it possible to obtain an answer to this question, without considering the mass? Cause what I did was just equate 1/2 mv^2 with 1/2 kA^2, the total energy of a spring system. Is that valid? Please, any advice at all. Thanks.