1. The problem statement, all variables and given/known data Late correction, this is the 2008 F=ma exam: http://www.aapt.org/Programs/contests/upload/olympiad_2008_fnet_ma.pdf A mass is attached to the wall by a spring of constant k. When the spring is at its natural length, the mass is given a certain initial velocity, resulting in oscillations of amplitude A. If the spring is replaced by a spring of constant 2k, and the mass is given the same initial velocity, what is the amplitude of the resulting oscillation? 2. Relevant equations Uh... This is the problem here. I might just be forgetful, but I cannot recall any equation relating amplitude and f, T, k, or v. T = 2∏√(m/k) is the most relevant formula I could recall. 3. The attempt at a solution Intuition led me to choose the correct answer: (1/√2)A I know if k is doubled, the amplitude will decrease. I had a feeling there is a relationship k ∝ A^2 given a constant v_initial and mass. Can anyone shed some light on this?