3 A particle \(P\) of mass 0.4 kg is attached to a fixed point \(O\) by a light elastic string of natural length 0.5 m and modulus of elasticity 20 N . The particle \(P\) is released from rest at \(O\).
- Find the greatest speed of \(P\) in the subsequent motion.
- Find the distance below \(O\) of the point at which \(P\) comes to instantaneous rest.