Probability — practice question

A particle $P$ with mass $0.3\,\text{kg}$ is fastened to one end of a light elastic string whose natural length is $0.6\,\text{m}$ and modulus of elasticity is $9\,\text{N}$. The string’s other end is fixed at a point $O$ on a smooth plane inclined at $30^\circ$ to the horizontal. $OA$ is the line of greatest slope on the plane, with $A$ lying below $O$, and $OA = 0.8\,\text{m}$. Particle $P$ is released from rest at $A$.