A light, elastic string, of natural length 1.8 m and modulus of elasticity 45 N, is attached to a ceiling at point G. The lower end of the string is attached to a particle, P, of mass 1.8 kg. A second light, elastic string, of natural length 0.9m and modulus of elasticity 35 N, is attached to the particle and then to the point H, where H is 4m vertically below G. The particle rests in equilibrium with both parts of the string taut.

a. Find the distance of P above H.

b. P is then pulled down a further 1m and released. Find the speed when the particle is 1.5 m above H.