Representation of data — practice question

A uniform triangular prism with weight $20\text{ N}$ is at rest on a horizontal table. $ABC$ is the cross-section through the prism’s centre of mass, with $BC = 0.5\text{ m}$, $AB = 0.4\text{ m}$, $AC = 0.3\text{ m}$ and angle $BAC = 90^\circ$. The vertical plane $ABC$ is perpendicular to the table edge. Point $D$ on $AC$ lies at the table edge, and $AD = 0.25\text{ m}$. One end of a light elastic string of natural length $0.6\text{ m}$ and modulus of elasticity $48\text{ N}$ is fixed to $C$ and a particle of mass $2.5\text{ kg}$ is attached to the other end of the string. The particle is let go from rest at $C$ and moves down vertically.