When the displacement of a particle executing S.H.M. is y, then its
K.E. = \(\frac{1}{2}\)mω2(A2 − y2)
And P.E. = \(\frac{1}{2}m\omega^2y^2\)
If K.E. = P.E.
then, \(\frac{1}{2}m\omega^2(A^2\,-\,y^2)=\frac{1}{2}m\omega^2y^2\)
Or 2y2 = A2
Or y = \(\frac{A}{\sqrt2}\)