A particle is executing SHM  After 2 seconds of crossin

SOLUTION

$y=A\sin \omega t$                   ;             $\frac{\sqrt{3}}{2}.A=A\sin \omega t$
$\sin \omega t=\frac{\sqrt{3}}{2}or\omega t=\frac{\pi }{3};$                           $\omega =\frac{\pi }{3t}=\frac{\pi }{6}$
$T=\frac{2\pi }{\omega }=\frac{2\pi }{\left(\frac{\pi }{6}\right)}=12;$                   T = 12 seconds.