Given Amplitude \(\mathrm{A}=7 \mathrm{cm}=0.07 \mathrm{m}\)

\(a_{\max }=g=\omega^{2} A\)

The frequency of piston

\(\mathrm{f}=\frac{\omega}{2 \pi}=\sqrt{\frac{\mathrm{g}}{\mathrm{A}}} \frac{1}{2 \pi}=\sqrt{\frac{1000}{7}} \frac{1}{2 \pi}=1.9 \mathrm{Hz}\)