A particle executes simple harmonic motion represented by displacement function as $x\left(t\right)=A\sin (\omega t+\varphi )$. If the position and velocity of the particle at $t=0s$ are 2 cm and $2\omega cm{s}^{-1}$  respectively, then its amplitude is $x\sqrt{2}cm$ where the value of $x$ is ______.