$\mathrm{v}_{\mathrm{y}}=\frac{\mathrm{dy}}{\mathrm{dt}}=\mathrm{a\omega} \cos \omega \mathrm{t}$
$\mathrm{v}_{\mathrm{z}}=\frac{\mathrm{d} z}{\mathrm{dt}}=\mathrm{a} \omega$
$\therefore \quad \mathrm{v}=\sqrt{\mathrm{v}_{\mathrm{x}}^{2}+\mathrm{v}_{\mathrm{y}}^{2}+\mathrm{v}_{\mathrm{z}}^{2}}=\mathrm{a} \omega \sqrt{2}$



$x = 3\,sin\, 20\pi t + 4\, cos\, 20\pi t$ ,
where $x$ is in $cms$ and $t$ is in $seconds$ . The amplitude is ..... $cm$