A particle \(P\) of mass \(0.2\,\text{kg}\) is attached to one end of a light elastic string of natural length \(0.75\,\text{m}\) and modulus of elasticity \(21\,\text{N}\). The other end of the string is attached to a fixed point \(A\) which is \(0.8\,\text{m}\) vertically above a smooth horizontal surface. \(P\) rests in equilibrium on the surface.
- Find the magnitude of the force exerted on \(P\) by the surface. [2]
\(P\) is now projected horizontally along the surface with speed \(3\,\text{m s}^{-1}\).
- Calculate the extension of the string at the instant when \(P\) leaves the surface. [3]
- Hence find the speed of \(P\) at the instant when it leaves the surface. [3]