The velocity of a particle executing SHM at any instant, is defined as the time rate of change of its displacement at that instant. where, ω is angular frequency, A is amplitude and x is displacement of a particle. Suppose that the new amplitude of the motion be A'. Initial velocity of a particle performs SHM, where, A is initial amplitude and ω is angular frequency, Final velocity therefore will be 7A/3

(https://clay6.com/qa/76697/a-particle-performs-simple-harmonic-motion-with-amplitude-a-its-speed-is-tr#)

(https://clay6.com/qa/76697/a-particle-performs-simple-harmonic-motion-with-amplitude-a-its-speed-is-tr#)