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