Explanation

(a) The maximum velocity of a particle performing SHM is given by $v = A\omega$, where $A$ is the amplitude and $\omega$ is the angular frequency of oscillation.
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 4.4 = (7 \times 10^{- 3}) \times \frac{2\pi}{T}$
$\Rightarrow \ \ \ \ T = \frac{7 \times 10^{- 3}}{4.4} \times \frac{2 \times 22}{7} = 0.01$ s