The position, velocity and acceleration of a particle executing simple harmonic motion are found to have magnitudes of 4 m, 2 ms^-1 and 16 ms^-2 at a…

The position, velocity and acceleration of a particle executing simple harmonic motion are found to have magnitudes of $\displaystyle 4 \mathrm{~m}, 2 \mathrm{~ms}^{-1}$ and $\displaystyle 16 \mathrm{~ms}^{-2}$ at a certain instant. The amplitude of the motion is $\displaystyle \sqrt{x}, \mathrm{~m}$ where $\displaystyle x$ is $\displaystyle \_\_\_\_$.