The ends of a light elastic string of natural length 0.8m and modulus of elasticity 2N are attached to fixed points A and B which are 1.2m apart at the same horizontal level. A particle of mass 0.3 kg is attached to the centre of the string, and released from rest at the mid-point of AB. The particle descends 0.32m vertically before coming to instantaneous rest.

i. Calculate A.

ii. Calculate the speed of the particle when it is 0.25m below AB.