$T=2 \pi \sqrt{\frac{\ell}{g}}$
$T^{\prime}=\frac{x}{2} T$
$2 \pi \sqrt{\frac{\ell}{2 g}}=\frac{x}{2} 2 \pi \sqrt{\frac{\ell}{g}}$
$\frac{1}{\sqrt{2}}=\frac{x}{2} \Rightarrow x=\sqrt{2}$
If the position and velocity of the particle at $t=0\, {s}$ are $2\, {cm}$ and $2\, \omega \,{cm} \,{s}^{-1}$ respectively, then its amplitude is $x \sqrt{2} \,{cm}$ where the value of $x$ is ..... .

