A particle executes simple harmonic motion with an amplitude of 4 cm. At the mean position, velocity of the particle is 10 cm / s. The distance of…

A particle executes simple harmonic motion with an amplitude of $\displaystyle 4$ cm. At the mean position, velocity of the particle is $\displaystyle 10 \mathrm{~cm} / \mathrm{s}$. The distance of the particle from the mean position when its speed becomes $\displaystyle 5 \mathrm{~cm} / \mathrm{s}$ is $\displaystyle \sqrt{\alpha} \mathrm{cm}$, where $\displaystyle \alpha=$ $\displaystyle \_\_\_\_$.