$t = \frac{T}{4} = \frac{1}{{4n}}$
==> $n = \frac{1}{{4t}} = \frac{1}{{4 \times 0.170}} = 1.47\,Hz$

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 ..... .