5 One end of a light elastic string of natural length 0.8 m and modulus of elasticity 24 N is attached to a fixed point \(O\). The other end of the string is attached to a particle \(P\) of mass \(0.3 \mathrm {~kg} . P\) is projected vertically upwards with speed \(4 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) from a position 1.2 m vertically below \(O\).

1. Calculate the speed of the particle at the position where it is moving with zero acceleration. [5
2. Show that the particle moves 1.2 m while moving upwards with constant deceleration.