At a given point of time the value of displacement of a simple harmonic oscillator is given as $\mathrm{y}=\mathrm{A} \cos \left(30^{\circ}\right)$. If amplitude is $40 \mathrm{~cm}$ and kinetic energy at that time is $200 \mathrm{~J}$, the value of force constant is $1.0 \times 10^{x} ~\mathrm{Nm}^{-1}$. The value of $x$ is ____________.