A light spiral spring of force constant K lies on a horizontal frictionless surface and has one end fixed to a vertical wall . A block P of mass 2.0kg placed against the free end of the spring is pushed a distance 5.0cm towards the wall with 10J of energy as illustrated in the diagram above. The block is released and after 0.25s it collides inelastically with a stationary block of mass 4.0kg. Calculate the (i) value of K: