\(\text { at } x=\frac{2 A}{3}\)

\(v=\omega \sqrt{A^2-\left(\frac{2 A}{3}\right)^2}=\frac{\sqrt{5} A \omega}{3}\)

New amplitude \(=\mathrm{A}^{\prime}\)

\(\mathrm{v}^{\prime}=3 \mathrm{v}=\sqrt{5} \mathrm{~A} \omega=\omega \sqrt{\left(\mathrm{A}^{\prime}\right)^2-\left(\frac{2 \mathrm{~A}}{3}\right)^2}\)

\(\mathrm{A}^{\prime}=\frac{7 \mathrm{~A}}{3}\)